JP2007258229A - Semiconductor particulate structure, and semiconductor device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin sealing tool for resin-sealing a plurality of semiconductor particulates together, and useful in forming a deep valley of sealing resin between the adjacent semiconductor particulates. <P>SOLUTION: The semiconductor particulate structure includes a plurality of semiconductor particulates provided at predetermined intervals on a plane, a plurality of apertures arranged like a mesh, and a meshy member having the semiconductor particulates placed in the respective apertures approximately at the center of the particulates and not in contact. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor technology and a resin sealing technology. More specifically, the present invention relates to a semiconductor fine particle structure and a semiconductor fine particle-lens composite structure useful for manufacturing a semiconductor device, and these structures, for example, The present invention relates to a semiconductor device such as a solar battery. The present invention also relates to a resin sealing method useful for manufacturing a semiconductor fine particle-lens composite structure and the like, and a solar cell manufacturing method using the resin sealing method.

  In recent years, a method for manufacturing a small and high-performance semiconductor device using a spherical and fine semiconductor has been proposed. A typical example of such a semiconductor device is a solar cell. For example, Patent Document 1 discloses that a plurality of semiconductor blocks each having a p-type and an n-type region are thread-shaped conductors that are in contact with the p-type and n-type regions. A granular solar cell characterized in that a weft yarn is used and a defective conductor is fixed with a cloth-like substrate configured as a warp yarn to form a module is described.

  Further, Patent Document 2 discloses that a plurality of spherical semiconductor cells are placed in a state where the spherical semiconductor cells are aligned and embedded in a mesh-like conductive member, and each spherical semiconductor cell and the mesh-like conductive member are placed in a conductive paste. And a method of manufacturing the solar cell, characterized in that the light-receiving surface of the spherical semiconductor cell is covered with an antireflection film.

  Further, Patent Document 3 is a photovoltaic power generation characterized in that a photoelectric conversion element made of spherical silicon is arranged in each of a plurality of recesses formed on a support, and the photoelectric conversion element is irradiated with reflected light from the inner surface of the recess. An apparatus is described.

  Furthermore, Non-Patent Document 1 and Patent Document 4 describe a spherical semiconductor integrated circuit comprising a semiconductor material formed in a substantially spherical shape and at least one electric circuit provided on the outer surface of the semiconductor material, and The manufacturing method is described.

JP-A-9-162434 (Claims, FIG. 2) JP 2001-267609 A (Claims, FIG. 6) JP 2002-164554 A (Claims, FIG. 1) JP-T-2001-501779 (Claims, FIG. 25) Ball Semiconductor's challenge, “Electronic Packaging Technology”, Vol. 17, no. 8-10. , August-October 2001, Technical Committee

  As mentioned above, solar cells and other semiconductor devices based on the use of numerous spherical semiconductor particles are already known. However, there are many unsolved problems in the method of casting a large number of fine spherical semiconductor particles arranged in a plane with a liquid sealing resin to form a single structure. Specifically, for some reason (for example, to form an electrical terminal on each semiconductor particle), so that the upper surface of those semiconductor particles is slightly out of the liquid surface of the sealing resin, It may be necessary to cast and cure the sealing resin. At that time, the height of the sealing resin rising to the upper surface of each semiconductor particle is mainly determined according to the wettability between the sealing resin and the semiconductor particle and the surface tension of the sealing resin, and adjacent to each other. If the distance between the semiconductor particles is determined, the height of the resin liquid surface between the semiconductor elements is also determined, but the interface shape of such a naturally formed liquid sealing resin is, for example, the temperature, humidity during casting, It is easily affected by factors such as the shape of the semiconductor particles and the surface condition of the semiconductor particles. When the semiconductor particles are arranged close to each other, the interface of the liquid sealing resin between the semiconductor particles is high. It is formed and the valley is shallow. That is, as long as the liquid interface as described above is left to the natural formation, there arises a problem that the sealing resin crawls up to the upper surface of the semiconductor particles due to the surface tension of the resin, the upper surface of the sealing resin rises, and the shallow concave portion It can only be formed. Further, since the resin sealing step is easily affected by variations in temperature, viscosity, lot, and the like at the time of casting, it is impossible to form a deep and stable valley of the sealing resin between the semiconductor particles. If a deep valley of the sealing resin can be formed between the semiconductor particles, the light reflecting film is coated on the entire upper surface of the sealing resin in a later process, so that light incident from the sealing resin side can be efficiently reflected by the light reflecting film. Therefore, when the obtained semiconductor particle structure is used for manufacturing a solar cell, the luminous efficiency of the solar cell can be increased.

  Accordingly, an object of the present invention is to provide a semiconductor sealing method capable of forming a deep valley of a sealing resin between semiconductors when a plurality of particulate semiconductors and the like are sealed with a liquid sealing resin.

  Another object of the present invention is to provide a sealing auxiliary member that can encapsulate semiconductors collectively in the implementation of such a semiconductor encapsulating method, is easy to handle, and has a good yield when manufacturing a semiconductor device. is there.

  Furthermore, the present invention provides a semiconductor sealing structure having a deep valley of the sealing resin between semiconductors, and a solar cell and other semiconductor devices having excellent light reflection efficiency using the semiconductor sealing structure. There is.

  Furthermore, this invention is providing the method which can manufacture the solar cell excellent in the light reflection efficiency correctly and simply with a sufficient yield.

  These and other objects of the present invention will be readily understood from the following detailed description.

The present invention includes a plurality of semiconductor microparticles arranged in a plane at a predetermined interval on one surface thereof,
A plurality of openings arranged in a mesh shape, and the semiconductor fine particles arranged in the respective openings at a substantially central position of the semiconductor fine particles and in a non-contact manner;
A semiconductor fine grain structure comprising:

In another aspect of the present invention, the semiconductor fine grain structure according to the present invention includes:
A sealing member made of a light-transmitting resin that seals the first region occupying almost half of the outer peripheral surface of the semiconductor fine particles and the mesh member,
A hemispherical lens body is configured by sealing the first region of the semiconductor microparticles included in the semiconductor microparticle structure with a predetermined thickness,
In the second region of the semiconductor microparticle opposite to the first region, the outer peripheral surface of the semiconductor microparticle is exposed, and the mesh member is apex between the adjacent semiconductor microparticles. The semiconductor microparticle-lens composite structure is characterized in that the parabolic meniscus is a sealing member formed by the surface tension of the resin.

  Furthermore, the present invention, in another aspect thereof, is a solar cell or other semiconductor device comprising the semiconductor fine particle-lens composite structure according to the present invention as one constituent element.

Furthermore, the present invention, in another aspect thereof, is a method for collectively sealing a plurality of semiconductor fine particles, comprising the following steps:
Disposing a plurality of semiconductor fine particles in a plane at a predetermined interval;
A net-like member having a plurality of openings arranged in a mesh shape is overlaid on the semiconductor fine particles, and the semiconductor fine particles are placed in respective openings of the net-like member at a position substantially at the center of the semiconductor fine particles. And forming a semiconductor fine grain structure arranged in a non-contact manner,
In a state where the curable resin is brought into contact with the portion to be resin-sealed of the semiconductor fine particle structure in an uncured state, and in a state where the contact state between the semiconductor fine particle structure and the curable resin is maintained, A resin sealing method comprising curing a curable resin to form a resin sealing member.

In addition, the present invention is a method for manufacturing a solar cell composed of a plurality of semiconductor microparticles each having a p-pole and an n-pole formed on each surface, and includes the following steps:
Disposing a plurality of semiconductor fine particles in a plane at a predetermined interval;
A net-like member having a plurality of openings arranged in a mesh shape is overlaid on the semiconductor fine particles, and the semiconductor fine particles are placed in respective openings of the net-like member at a position substantially at the center of the semiconductor fine particles. And forming a semiconductor fine grain structure arranged in a non-contact manner,
Contacting the curable resin in an uncured state with the resin-sealed portion of the semiconductor microparticle structure;
Forming a resin sealing member by curing the curable resin while maintaining a contact state between the semiconductor fine particle structure and the curable resin; and p in the non-resin sealing portion of the semiconductor fine particle. Forming an electrode and an n electrode lies in a method of manufacturing a solar cell.

  According to the present invention, as understood from the following detailed description, when sealing a plurality of semiconductor fine particles with a liquid sealing resin, the liquid surface shape of the sealing resin can be managed, A deep valley of the sealing resin can be stably formed between the semiconductor fine particles, and the semiconductor fine particles can be quickly and surely sealed with the resin. In addition, the sealing resin used in the present invention is made of a transparent, for example, thermosetting resin or photo-curable resin, so that the resin is used in a liquid state and then easily cured by application of heat or light. Therefore, semiconductor encapsulation can be easily performed. Moreover, since a favorable light transmission characteristic can be provided with respect to the obtained resin sealing body, it can utilize advantageously for manufacture of various semiconductor devices including a solar cell. In fact, when the semiconductor fine grain structure of the present invention having good handleability is used, a semiconductor device can be manufactured easily and reliably with a high yield.

  More specifically, it is possible to form the liquid surface of the sealing resin in the valleys between the semiconductor fine grains in a deep state. Further, by freely controlling this interface, that is, the meniscus, a deep valley suitable for the purpose can be formed so that light can be incident stably. Thus, if a light reflecting film is formed on the resin surface after curing in a later step, for example, by vapor deposition of silver, an extremely efficient light reflecting shape can be given to individual semiconductor fine particles.

  In addition, since the mesh member can efficiently flow current when it is formed from a conductive material, for example, when the light reflecting film is formed by metal deposition, the metal deposition surface and the conductive mesh member are connected in parallel. As a result, power loss can be reduced.

  Furthermore, since the control of the surface of the liquid sealing resin can be limited in units of the mesh of the mesh member, even when there is a defect in the shape and position of the semiconductor fine particles when the area is increased, the result of obtaining the defect, etc. Will not spill over.

  Furthermore, the semiconductor fine particle-lens composite structure is strong because the mesh member encapsulated therein serves as a reinforcing material, and is strong, and increases the mechanical strength of solar cells and other semiconductor devices using the same. be able to. Further, when the mesh member is formed of a flexible material, the semiconductor fine particle-lens composite structure having three-dimensional curved surface followability can be used by being deformed into various shapes.

  In addition, when a light reflecting film having a high light reflectance is formed by applying aluminum plating or silver plating to the mesh member or a mirror surface treatment is applied, the sealing resin is used because of the high light reflectance derived from the mesh member itself. It is possible to effectively capture the light incident on the light and focus it on the semiconductor fine particles, thereby improving the light conversion efficiency.

  Further, in the net-like member, when the wettability of the liquid sealing resin is improved by changing the opening pattern of at least the opening or by performing a surface treatment, the depth of the meniscus (recess) formed in the sealing resin And the light reflection efficiency can be optimized.

  The semiconductor fine particle structure, the semiconductor fine particle-lens composite structure, the semiconductor device, the resin sealing method, and the solar cell manufacturing method according to the present invention can be advantageously implemented in various forms. Hereinafter, the present invention will be described by way of preferred embodiments with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

  A first aspect of the present invention is a semiconductor fine grain structure including a plurality of semiconductor fine grains. The semiconductor fine grain structure of the present invention has a plurality of semiconductor fine grains arranged in a plane at a predetermined interval and a plurality of openings arranged in a mesh shape, and the semiconductor in each opening. It is characterized in that the fine particles include a net-like member arranged in a non-contact manner at a substantially central position of the semiconductor fine particles. Here, “microparticle” means a sphere or fine particles or powder having a cross-sectional shape similar to that of a sphere as described below.

  The semiconductor fine grain structure of the present invention can be advantageously used in the production of various semiconductor devices. Examples of semiconductor devices suitable for implementing the present invention include, but are not limited to, those listed below, and include solar cells, light emitting diodes, and optical sensors. That is, the semiconductor fine particle structure of the present invention can be used for manufacturing these semiconductor devices after it is sealed with a resin to form a semiconductor fine particle-lens composite structure. The semiconductor fine particle structure of the present invention can also be called a “semiconductor device precursor (particularly, a first semiconductor device precursor)” in view of such applications.

  FIG. 1 is a cross-sectional view showing a preferred embodiment of a semiconductor fine grain structure according to the present invention. The semiconductor fine particle structure shown in the figure can be used particularly for the manufacture of solar cells using silicon fine particles. The semiconductor fine particle structure 10 is shown with three semiconductor fine particles 1 for simplification in the drawing, but usually includes a larger number of semiconductor fine particles 1. The semiconductor microparticles 1 are substantially spherical as illustrated, but are not limited to the illustrated form. The semiconductor fine particles 1 may be further deformed, may be provided with corners, or may have a teardrop shape or the like, although depending on manufacturing conditions. In addition, although the semiconductor fine particle 1 of illustration shows the layer of the thin film surrounding the outer periphery, since this is planning manufacture of a silicon solar cell, it represents the n-type semiconductor layer already formed. . That is, a pn junction is formed by the n-type semiconductor layer and the p-type semiconductor layer constituting the core portion of the semiconductor microparticle 1.

  As is understood from the photograph of FIG. 3, the semiconductor microparticles 1 are arranged at predetermined intervals in a planar shape, as is generally performed in solar cells. The number of semiconductor microparticles 1 is determined by the size of the microparticles, the concentration factor, and the size of the solar cell, but is usually in the range of about 1 to 2.5 million, and preferably about 1 to 70,000. Range. As an example, when the semiconductor device is an optical sensor or the like, the number of semiconductor microparticles 1 is usually one. Further, in the solar cell, when the diameter of the semiconductor microparticles 1 used in the solar cell is 0.5 mm, the condensing magnification is 4 times, and the size of the solar cell panel is 1 m × 2 m, the number of the semiconductor microparticles 1 is For example, it is around 2.5 million pieces. Furthermore, when the diameter of the semiconductor fine particles 1 is 1.0 mm, the light condensing magnification is 4.4 times, and the size of the solar cell panel is 50 cm × 50 cm, the number of the semiconductor fine particles 1 is, for example, 70,000. It is around.

  Each of the semiconductor fine particles 1 is supported by a support (also referred to as an arrangement plate) 4 for temporary fixing in order to stably hold them until they are used for manufacturing a semiconductor device. For temporary fixing, an adhesive material such as an adhesive is advantageously used. The support (also referred to as an arrangement plate) 4 includes a spacer 3 for use as a jig when a semiconductor fine particle-lens composite structure is produced from the semiconductor fine particle structure 10.

  The semiconductor fine particle structure 10 of the present invention includes a net-like member 2 in combination with the semiconductor fine particles 1. The mesh member 2 is usually in the form of a sheet or a plate, and is preferably flexible for convenience of handling and workability. Further, the net-like member 2 has the above-described semiconductor microparticles 1 resin-sealed and has a parabolic meniscus peculiar to the present invention (the depth formed of the sealing resin formed between adjacent semiconductor microparticles 1. In order to form a recess), an opening 12 for taking in each of the plurality of semiconductor fine particles 1 is provided. The openings 12 are preferably arranged in a mesh pattern corresponding to the arrangement pattern of the semiconductor microparticles 1 as shown in FIG. As shown in the drawing, the semiconductor microparticles 1 can be disposed in the respective openings 12 at positions substantially in the center of the semiconductor microparticles 1 in a non-contact manner. In particular, in the semiconductor fine particle structure 10 of the present invention, it is important that the semiconductor fine particles 1 are not in contact with the mesh member 2.

  Similar to the semiconductor fine particles 1, the net-like member 2 holds the members stably until it is used for manufacturing a semiconductor device, and prevents the distance between the semiconductor fine particles from fluctuating. It is temporarily fixed. The temporary fixing means 13 in this case is not particularly limited. For example, a double-sided pressure-sensitive adhesive tape can be advantageously used to ensure a predetermined thickness, but a spacer or other member having a predetermined thickness may be used if necessary.

  The net-like member 2 can be used without being temporarily fixed as necessary. For example, the mesh member 2 may be configured to be movable. In such a case, after the semiconductor fine particles are immersed to an appropriate position of the liquid sealing resin, the mesh member is brought into contact with the liquid surface and pushed down. As a result, the liquid level can be lowered to a predetermined position.

  Next, the configuration of the semiconductor fine particle structure of the present invention will be described in more detail.

Semiconductor microparticles Semiconductor microparticles can be formed from various semiconductor materials and in various shapes and sizes, depending on their ultimate application. First, silicon (Si) is usually used as a semiconductor material, but other materials may be used if necessary. Suitable semiconductor materials include, but are not limited to, those listed below, and compound semiconductors such as gallium arsenide (GaAs), gallium phosphide (GaP), and gallium aluminum arsenide (GaAlAs).

  The semiconductor microparticles are usually in the form of spheres or nearly spheres, or else in the form of deformed spheres. Suitable forms of semiconductor fine particles are not limited to those listed below, but fine particles such as true spheres, distorted true spheres, teardrops, and the like, and these fine particles are further provided with fine protrusions such as confetti Can be mentioned. Moreover, as a special form of the semiconductor fine particles, fine particles such as a cube and a rectangular parallelepiped can be cited. According to the knowledge of the present inventor, teardrop semiconductor fine particles are particularly suitable in terms of processability and obtained optical characteristics.

  Semiconductor fine particles can be used in various dimensions. The size of the semiconductor fine particles is usually in the range of about 0.2 to 3.0 mm, and preferably in the range of about 0.8 to 1.1 mm, as viewed from the average diameter of the spheres. In accordance with recent advances in semiconductor manufacturing technology and processing technology, finer semiconductor fine particles may be used if necessary. In manufacturing the semiconductor fine particle structure, it is preferable that the respective semiconductor fine particles have substantially the same shape and dimensions.

  Semiconductor fine particles can be produced by using various production methods that are commonly used for producing semiconductor fine particles. A suitable semiconductor manufacturing method is, for example, a method in which a molten semiconductor material is freely dropped by gravity and fine particles are formed during the dropping. This method is simple to implement, the apparatus is not complicated, and in principle there is no cut loss. Specifically, this method includes, for example, melting a semiconductor material (eg, silicon) in a melting furnace crucible, and then bringing the molten semiconductor material to a predetermined height (eg, about 10 from the microparticle recovery surface). It can be produced by free-falling by gravity from a height of ˜15 m. The free-falling step can be advantageously performed, for example, by dropping molten semiconductor material at high speed from a nozzle under pressure in an atmosphere of an inert gas such as argon. The molten semiconductor material is spheroidized by surface tension during free fall and further solidified. Therefore, finally, high-quality semiconductor fine particles having a desired shape and size can be obtained. Preferably, in the practice of the present invention, the semiconductor fine particles obtained in this way can be used without performing complicated mechanical polishing. That is, the semiconductor fine particles are usually as manufactured, and need not be subjected to polishing or molding.

  After the semiconductor fine particles are manufactured, the semiconductor fine particles can be subjected to any surface treatment according to the final purpose of use and the like, and the subsequent process can be facilitated. For example, when the semiconductor fine particles are silicon fine particles and used for the manufacture of a solar cell, an n layer is formed on the surface of the silicon fine particles by phosphorus diffusion, and a pn junction is simultaneously formed. Further, the silicon oxide film is formed after the impurities at the crystal grain boundaries are inactivated by a mixed gas of hydrogen and nitrogen. Finally, a titanium oxide film, a silicon nitride film, or the like is formed on the silicon oxide film as an antireflection film.

More specifically, with reference to a preferred embodiment, the semiconductor fine particles are silicon fine particles, and when used for manufacturing a solar cell, the size of the silicon fine particles is about 1 mm ± 0.1 mm, Its shape is a teardrop type. The teardrop type silicon microparticles are approximately 1.5 times as long as the part that can be approximated to a sphere, including the corner part, and there are variations in the corner appearance and length as well as the sphere size variation. However, there is no problem in implementing the present invention. The main component of the silicon fine particles is a p-type semiconductor layer (boron concentration 1 × 10 ¹⁶ atoms / cm ³ ), and phosphorus diffusion is performed on this to form an n-type semiconductor layer from the surface to about 300 to 400 nm. Further, after inactivating (passivation) the grain boundaries with a hydrogen / nitrogen mixed gas, a silicon oxide thin film is formed on the surface with a film thickness of, for example, about 8 nm as a protective film, and a titanium oxide film is formed on the outside thereof. For example, it is formed with a film thickness of 86 nm.

As described above, the mesh member has a plurality of openings arranged in a mesh shape, and is preferably used in the shape of a net.

  In the mesh member, the openings are preferably arranged in regular rows and columns, and the semiconductor microparticles are positioned approximately in the center of each opening. The opening may have an arbitrary opening pattern, but is preferably a circular, rectangular, triangular, hexagonal or polygonal opening pattern. The size of the opening is not particularly limited as long as the semiconductor fine particles can be disposed in the opening without contact. The size (maximum diameter) of the opening is usually in the range of about 1 to 8 mm, and preferably in the range of about 1.5 to 2.4 mm.

  The mesh member is usually used in the form of a sheet, a film or a plate. The size of these members can be arbitrarily changed according to the end use or the size of the final product. For example, in the case of a solar cell, the size of the mesh member is usually in the range of about 1 mm to 200 cm, and preferably in the range of about 1 to 50 cm. In particular, in the case of the present invention, the mesh member can serve as a reinforcing material and can also ensure an appropriate flexibility. Therefore, a larger solar cell can be obtained with a larger yield by using a larger mesh member. It is noteworthy in that it can provide. Accordingly, the size of the mesh member as described above does not limit the scope of the present invention, and a larger mesh member can be used as necessary.

  The net member is not limited in its material or material as long as the intended purpose of reinforcing the structure and forming a parabolic meniscus is achieved. The net-like member is made of a hard material so that the degree of deformation is reduced when considering deformation caused by pushing up the sealing resin, which is liquid, and deformation caused by curing shrinkage of the sealing resin, or It is preferably made of a thick material. Usually, it is advantageous to form the mesh member from a metal material in consideration of such properties and workability. In addition, the net member need not be a metal material, and other materials such as plastic materials and glass can also be used, particularly if the use is for the purpose of forming a parabolic meniscus by interface control. . Although not limited to those listed below, suitable metal materials include, for example, aluminum, copper, nickel, silver, stainless steel, iron and the like, and suitable plastic materials include, for example, polyimide, polycarbonate, acrylic resin, Including polyester resin and polyamide resin. These materials may be used as they are, or may be subjected to any surface treatment.

  The opening of the mesh member can be processed according to any technique. For example, when the mesh member is formed of a metal material, a metal net having a desired opening pattern can be easily formed by punching a metal sheet having a predetermined thickness. . When the mesh member is formed from a plastic material, a desired plastic net can be easily formed by molding the molten plastic material using a mold having a protrusion corresponding to the opening.

  More specifically, the opening pattern of the mesh member takes into account the close-packing of semiconductor microparticles, that is, the obtained hemispherical lens, for example, as shown in FIG. An arranged honeycomb structure is preferable. In this case, the net member is in the form of a net, the net line width is approximately 150 μm, and the thickness is approximately 50 to 200 μm. As for the line width of the net, there should be a width that does not wet the top surface of the net when the liquid surface of the sealing resin used in liquid form is pressed down, but this depends on the amount of the liquid surface pressed down.

  In a preferred embodiment of the present invention, the mesh member is preferably formed of a conductive metal material such as aluminum or silver. This is because these metal materials have good electrical conductivity, and the ionized material not only causes a significant loss in the properties of silicon but also works effectively in terms of light reflection.

  Further, it is preferable that the net member has light reflectivity at least on the surface thereof. This is because the net-like member has light reflectivity, so that light incident on the solar cell or other semiconductor device can be more effectively reflected, and the power generation efficiency can be further improved. The means for imparting light reflectivity is not limited, and any surface treatment can be included. A suitable surface treatment method is, for example, gloss treatment such as plating or reflection treatment. For example, light reflectivity can be improved by forming a thin film of silver plating on the surface of a member made of copper.

  Further, the side surface of the mesh member is preferably flat and close to a mirror surface unless special treatment is performed. However, in the case where the directivity is not given when reflecting incident light, it is possible to make the surface moderately rough so as to be scattered light.

  Furthermore, the reticulate member has at least an opening portion, the wettability with respect to the resin used for sealing the reticulate member and the semiconductor fine particles is controlled, and has two properties of positive hydrophilicity and negative hydrophilicity (water repellency). Is preferably provided in a harmonized form. For example, wettability between the mesh member and the sealing resin can be controlled by performing a treatment for imparting hydrophilicity or water repellency to the side surface or bottom surface of the mesh member. This treatment is effective in narrowing the line width of the mesh member as compared with the case of no treatment. If the line width of the mesh member is too wide, it may be a shadow of the incident optical path, so the upper limit of the line width will be determined by the cell structure of the solar cell, for example.

Support The above-described semiconductor fine particles and the net-like member are preferably used in a state where they are temporarily held on a support, also referred to as an arrangement plate, in the present invention. In other words, since the support is a member used for temporary fixing and not included in the final product, it can be formed from any material. Usually, the support is not deformed when supporting the semiconductor fine particles and the net-like member, and is in the form of a flat plate from various materials excellent in handleability, such as metal materials, plastic materials, glass and other ceramic materials. Can be formed. Moreover, it is preferable that the support can be used repeatedly without being discarded.

  In addition, on one side of the support, in order to facilitate positioning and fixing of the semiconductor fine particles, a shallow dish-shaped recess or depression or pore is provided in advance at a position where the semiconductor fine particles should be temporarily fixed. In addition, the recesses or the like contain a medium suitable for temporarily fixing the semiconductor fine particles in advance or immediately before use, preferably an adhesive material such as an adhesive or an adhesive paste in a trace amount. It is preferred that This is because the semiconductor fine particles can be fixed on the support until the support is separated from the semiconductor fine particles by the adhesive, and the semiconductor fine particle-lens composite structure can be manufactured with high yield.

  An example of using silicon microparticles (here, teardrop-type silicon microparticles) is provided as an arrangement plate made of quartz glass having holes in a staggered pattern. Next, the silicon fine particles are arranged so that the corners of the silicon fine particles are put in the pores of the arrangement plate. In order to prevent silicon fine particles from falling when the arrangement plate is turned upside down, the pores of the arrangement plate are filled with light grease.

  A bonding material is also used on one side of the support to temporarily fix the mesh member. The bonding material used here is not particularly limited as long as it can stably temporarily fix the mesh member, and includes, for example, a double-sided pressure-sensitive adhesive tape or grease. For example, a metal net is attached to a support with a double-sided adhesive tape and fixed.

  A spacer is also used on one side of the support. The spacer will be described in detail below. In the manufacture of the semiconductor microparticle-lens composite structure, the center of the hemispherical lens body formed by the mold and the position of the silicon microparticles are considered in consideration of optical conditions. This is useful for accurate position adjustment when performing optimum positioning. The spacer can be formed from various materials like other members, but it is usually useful to form the spacer by molding from a plastic material such as polyimide.

  The present invention resides in a semiconductor fine particle-lens composite structure using the semiconductor fine particle structure in addition to the semiconductor fine particle structure. The semiconductor microparticle-lens composite structure is closer to the form of the semiconductor device, and in response to the above-described semiconductor microparticle structure being referred to as a “first semiconductor device precursor”, It can be called a “semiconductor device precursor”.

  The semiconductor fine particle-lens composite structure according to the present invention seals the semiconductor fine particle structure according to the present invention as described above, the first region that occupies almost half of the outer peripheral surface of the semiconductor fine particle, and the mesh member. And a sealing member made of a light-transmitting resin. Since the details of the semiconductor fine grain structure are as described above, repeated description thereof is omitted here.

  FIG. 2 is an example of a semiconductor fine particle-lens composite structure according to the present invention produced using the semiconductor fine particle structure of FIG. 1, and therefore, it can be used for manufacturing a solar cell using silicon fine particles. it can. The semiconductor fine particle-lens composite structure 20 seals the vicinity of the semiconductor fine particles 1 of the semiconductor fine particle structure 10 (see FIG. 1) after removing the support 4 with a sealing member 5 in a predetermined pattern. It is characterized by that. The sealing member 5 forms a condensing layer as a whole, and in the first region of the semiconductor microparticle 1 (region below the mesh member 2), the surface of the semiconductor microparticle 1 has a predetermined thickness. The hemispherical lens body 15 is formed by coating with

  The sealing member 5 includes electrodes for constituting a solar cell and other semiconductor devices in a second region (region above the mesh member 2) opposite to the first region of the semiconductor microparticles 1. In order to form other components, the exposed outer peripheral surface is defined without covering the semiconductor fine particles 1. Further, the sealing member 5 forms a light reflector for reflecting the light incident on the sealing member 5 and concentrating it on the semiconductor fine particles 1 in the same second region. A parabolic meniscus 16 having a vertex p at or near the mesh member 2 is defined. The formation of the parabolic meniscus 16 is derived from the surface tension of the liquid sealing resin before curing, as will be described below. Further, although not shown in FIG. 2, in the second region, the outer peripheral surface of the semiconductor microparticle 1 and the surface of the sealing member 5 adjacent to the semiconductor microparticle 1 are, for example, a silver plating film covering these surfaces. It is preferable to further have a reflective film. This is because the effect of concentrating the light incident on the sealing member 5 on the semiconductor microparticles 1 can be further enhanced by this reflective film.

  The sealing member is preferably made of a material exhibiting sufficiently high light transmittance when used in a solar cell or other semiconductor device as a final product. This is because, for example, in a solar cell, a light beam from the outside needs to enter the lens body constituted by the sealing member and efficiently enter semiconductor fine particles. In other words, the sealing member needs to have high transparency = transparency at such a level that light transmission sufficient for the operation of the semiconductor device can be obtained. Therefore, the sealing member can be formed from any curable resin in which the obtained cured product exhibits high transparency. The curable resin may be a photocurable resin or a thermosetting resin depending on the curing mechanism. For example, when it is desired to shorten the curing time, it is not limited to those listed below, but UV curing of photo-curing resins such as acrylic resins, epoxy resins, and various modified resins thereof. It is recommended to use a curable resin or an electron beam curable resin such as an acrylic resin. On the other hand, the thermosetting resin is not limited to those listed below, but examples thereof include an acrylic resin and an epoxy resin.

  In the practice of the present invention, the curable resin as described above is preferably a liquid having an appropriate viscosity. This is because the curable resin is usually used by being cast into a mold having a recess or cavity having a shape and size corresponding to a hemispherical lens body to be formed. Although the viscosity of the liquid curable resin can be changed in a wide range, it is usually preferably less than 1,000 P, and more preferably around 40 P. When the viscosity of the curable resin is too high, the handleability is lowered, and defoaming or the like becomes difficult.

  In addition, the curable resin has a strong adhesive force with a silicon or titanium oxide film of a semiconductor fine particle (for example, silicon fine particle) to which a sealing member formed therefrom is to be adhered, The craving force on the grains is not too high, the curability of the mirror surface is sufficient, the water absorption is low, the linear expansion coefficient is not too high, the cure shrinkage is not too high, It is desirable that it is not brittle even in a thin state, is tough if possible, and is free of toxic components.

  FIG. 4 is a photograph of the semiconductor fine particle-lens composite structure of the present invention taken from the side of the mesh member. In the example shown in the figure, an aluminum product having a honeycomb structure in which regular hexagonal openings are arranged in a staggered manner. A net is used as a mesh member. Also, for the sake of explanation, semiconductor fine particles (silicon fine particles) are not arranged in a part of the regular hexagonal opening, but as can be understood from the figure, each silicon fine particle is located at substantially the center of the opening. Located and not in contact with the net.

  FIG. 5 schematically shows the liquid level profile of the sealing resin 5 in the vicinity of the semiconductor fine particles 1 in the semiconductor fine particle-lens composite structure of the present invention produced using a net-like member. FIG. 6 is an enlarged photograph (100) showing an actual liquid level profile in the vicinity of the semiconductor fine particles of the cast liquid encapsulating resin in the semiconductor fine particle-lens composite structure produced using the mesh member. Times). This photograph is a result of observing the shape of the sealing resin with a microscope by cutting and polishing the cell after curing the sealing resin. In FIG. 6, the electrode portion is removed from the semiconductor fine particles in the process of grinding the cell.

  As can be understood from these drawings, when the semiconductor fine particle-lens composite structure of the present invention is manufactured using the mesh member according to the present invention, a deep concave portion having the apex p on the upper surface of the mesh member 2 ( (Parabolic meniscus) can be formed in the sealing resin 5 between the adjacent semiconductor microparticles 1. Here, when the shape of the semiconductor microparticle 1 is approximated to a sphere excluding corners, when the diameter is 1 mm, the distance h from the apex p of the parabolic meniscus 16 to the upper end of the semiconductor microparticle 1 is It can be taken up to about 550 μm. For example, when the distance h is 500 μm, the depth m of the parabolic meniscus 16, that is, the distance from the apex p of the parabolic meniscus 16 to the upper end of the encapsulating resin 5 of the semiconductor fine particles 1 is About 250 μm. In addition, these numerical values are the results of measuring each distance by using a microscope and observing the phenomenon of pushing down the liquid level from the side when forming a parabolic meniscus (pressing down the liquid level of the liquid sealing resin). It is. Such measured values can also be evaluated from the photograph in FIG.

  According to the present invention, as described above, a parabolic meniscus having a depth suitable for light reflection can be easily and accurately formed on a large number of semiconductor microparticles, and moreover, The pattern and depth of the parabolic meniscus obtained can be easily controlled by changing the shape, configuration, and arrangement state of the net-like member and the semiconductor fine particles.

  FIG. 7 corresponds to FIG. 5 which is an example of the present invention, but in a semiconductor microparticle-lens composite structure manufactured without using a mesh member for comparison, the sealing resin 5 in the vicinity of the semiconductor microparticle 1 is shown. A liquid level profile is shown typically. FIG. 8 corresponds to FIG. 6 which is an example of the present invention, but for comparison, a semiconductor microparticle-lens composite structure manufactured without using a net-like member was casted with a liquid encapsulating resin semiconductor microparticle. It is an enlarged photograph (100 times) which showed the liquid level profile in the grain vicinity. In FIG. 8, since the corners of the semiconductor fine grains appear on the upper side of the photograph, the exposed part is observed to be large, but for comparison with the examples of FIGS. 5 and 6, as shown in FIG. The semiconductor microparticles were fitted with a sphere having a diameter of about 1 mm, and the dimensions were measured.

  As understood from these drawings, when a semiconductor fine particle-lens composite structure is produced without using a mesh member according to the conventional method, the surface of the sealing resin 5 between adjacent semiconductor fine particles 1 Only a very shallow depression can be formed, and it is impossible to form a deep recess (parabolic meniscus) as in the present invention. Actually, when the diameter of the semiconductor microparticle 1 is about 1 mm, the distance h from the lowest level of the liquid surface of the sealing resin 5 to the upper end of the semiconductor microparticle 1 is about 250 μm. The distance m from the lowest level of the liquid level to the upper end of the encapsulating resin 5 that craws up with the semiconductor fine particles 1 is about 50 μm.

  The present invention also resides in a semiconductor device provided with the above-described semiconductor fine particle-lens composite structure of the present invention. The semiconductor device of the present invention is not particularly limited as long as it includes the semiconductor fine particle-lens composite structure of the present invention, but preferably a solar cell, a light emitting diode, an optical sensor, or the like.

  The semiconductor device of the present invention is more preferably a solar cell. The solar cell of the present invention has a semiconductor fine particle-lens composite structure of the present invention in its main part, and a p-electrode and an n-electrode are formed on the respective surfaces of the semiconductor microparticles. A structure similar to that of a solar cell can be provided. In addition, since the general structure etc. of a solar cell are demonstrated in detail in patent documents, technical literature, etc., description here is abbreviate | omitted.

  FIG. 9 is a cross-sectional view showing a preferred embodiment of a solar cell (part) according to the present invention. The solar cell 30 includes a hemispherical lens body 15 formed of a transparent sealing member 5 on the surface, and light (hν) enters from above. Light incident on the solar cell 30 is reflected by the reflective film 31 formed by vapor deposition from nickel, silver or the like, and is concentrated on the semiconductor microparticles 1 and can contribute to power generation. The solar cell 30 includes a protective layer 32, an insulating layer 33, and an electrode layer 34. The protective layer 32 can be formed from an arbitrary resin such as an acrylic resin or an epoxy resin, and the insulating layer 33 can be formed from an arbitrary insulating resin such as a polyimide resin or an epoxy resin. 34 can be formed of any conductive metal such as aluminum or silver, or can be formed of any material provided with a conductive metal. These layers can be easily formed using a conventional film forming technique such as sputtering or vacuum deposition. Furthermore, although omitted for simplification of the drawings, other layers, parts, and the like may be provided in the same manner as a conventional solar cell. For example, although not shown, the upper surface of the hemispherical lens body 15 (the sunlight side indicated by an arrow) may be covered with a protective sheet having light transmittance and weather resistance.

  When the solar cell of the present invention as shown in the figure is used, the amount of light received by the semiconductor microparticles is remarkably derived from the formation of a parabolic meniscus having a depth capable of giving an extremely efficient light reflection shape. Therefore, the luminous efficiency of the solar cell can be significantly increased. This effect can be easily understood from the ray diagram of FIG. 15 described below.

  Furthermore, the present invention resides in a method for encapsulating a plurality of semiconductor fine particles at once. The resin sealing method of the present invention can be advantageously used for the production of various structures containing semiconductor fine particles, and in particular for the production of the semiconductor fine particle-lens composite structure of the present invention as described above. It can be used advantageously.

The resin sealing method according to the present invention includes the following steps:
Disposing a plurality of semiconductor fine particles in a plane at a predetermined interval;
A net-like member having a plurality of openings arranged in a mesh shape is overlaid on the semiconductor fine particles, and the semiconductor fine particles are placed in respective openings of the net-like member at a position substantially at the center of the semiconductor fine particles. And forming a semiconductor fine grain structure arranged in a non-contact manner,
In a state where the curable resin is brought into contact with the portion to be resin-sealed of the semiconductor fine particle structure in an uncured state, and in a state where the contact state between the semiconductor fine particle structure and the curable resin is maintained, Curing the curable resin to form the sealing member can be advantageously carried out by sequentially carrying out.

  In the above resin sealing method, in the step of arranging a plurality of semiconductor fine particles at a predetermined interval in a plane, it is advantageous to use a support for temporarily fixing the semiconductor fine particles as described above. is there. Moreover, this support body can be advantageously used as a temporary fixing means for the mesh member when the mesh member is superimposed on the semiconductor fine particles. The support can be removed and reused as necessary after forming the semiconductor fine particle-lens composite structure through the above-described series of steps.

  In the resin sealing method of the present invention, the curable resin may be a thermosetting resin or a photocurable resin as described above.

  Furthermore, in the resin contact step, it is preferable to push the semiconductor fine grain structure into a mold containing a curable resin. However, if another molding method is used, a method suitable for the molding method to be used can be arbitrarily used instead of such a method.

  Furthermore, in the resin curing step, a hemispherical lens body formed from a resin in which the first region occupying almost half of the outer peripheral surface of the semiconductor microparticles is sealed with a predetermined thickness, and adjacent semiconductor microparticles. It is preferable to form a resin sealing member provided with a parabolic meniscus having a net-like member at the apex formed by the surface tension of the resin between the grains.

  FIG. 10 sequentially shows a preferred embodiment of a method for producing a semiconductor fine particle-lens composite structure based on the resin sealing method of the present invention. Here, the semiconductor microparticle-lens composite structure is specifically designed for the manufacture of silicon solar cells, and therefore the semiconductor microparticle is a silicon microparticle.

  First, the silicon fine grain structure 10 shown in FIG. Here, the silicon fine particles 1 are produced by free-falling molten silicon in an argon atmosphere from a height of about 15 m. The diameter of the silicon microparticle 1 is about 1 mm. In the obtained silicon microparticle 1, an n layer is formed by phosphorus diffusion and an np junction is simultaneously formed. After inactivating impurities at the crystal grain boundaries with a mixed gas of hydrogen and nitrogen, oxidation is performed to form a thin silicon oxide film, and subsequently a titanium oxide film is formed as an antireflection film.

  Next, a support (glass plate) 4 made of quartz glass having holes in a staggered manner is prepared, and the silicon microparticles 1 are formed by inserting the corner portions of the silicon microparticles 1 prepared previously into the respective holes. Deploy. In order to prevent the silicon microparticles 1 from falling when the glass plate 4 is turned upside down, the grease is thinly buried in the holes of the glass plate 4. After the arrangement of the silicon microparticles 1 is completed, a mesh member (aluminum net having a regular hexagonal opening) 2 is attached and fixed to the glass plate 4 with a double-sided adhesive tape 13. Here, alignment is performed so that the silicon microparticles 1 of the glass plate 4 come to the center of the honeycomb net 2. Moreover, although the double-sided adhesive tape 13 is used for fixing the net 2, an adhesive or grease may be used instead. Further, instead of the method of fixing the net 2 to the glass plate 4, the net 2 can be installed independently of the glass plate 4. In that case, a jig is also required in consideration of the arrangement with a mold for producing a silicon microparticle-lens composite structure used in a subsequent process. In addition, since the optimum position of the center of the hemispherical lens body formed by the mold and the silicon microparticles is determined by optical conditions, the plastic spacer 3 is also attached to the glass plate 4 for this position adjustment. .

  Further, a mold 21 for producing a silicon microparticle-lens composite structure shown in FIG. The mold 21 is provided with a concave portion having a shape and a dimension corresponding to a target hemispherical lens body, and can be manufactured with an accurate dimension by wire cutting of steel. Next, after a fluorine-based release material is sprayed on the resin injection surface of the mold 21, a wiping process is performed. After completing the mold release process of the mold 21, a frame 22 holding the sealing resin is attached to the mold 22, and a necessary amount of the liquid sealing resin 5 is poured. Here, the liquid sealing resin 5 is an ultraviolet curable resin.

  Subsequently, as shown in FIG. 10 (A), the mold 21 and the side of the glass plate 4 are aligned with a jig (not shown) having two sides that are perpendicular to each other, and the position is shifted. The glass plate 4 is lowered onto the mold 21 while preventing it from occurring. Swelling of the sealing resin 5 occurs at the moment when the silicon fine particles 1 come into contact with the liquid surface of the liquid sealing resin 5, but this is suppressed by the net 2. By lowering the glass plate 4 to the set depth, a free interface of the sealing resin 5 is formed between the silicon microparticles 1 and the net 2. In the case of the present invention, since the spacer 3 is attached to the glass plate 4 with the upper surface of the mold 21 as a reference, the liquid level control of the liquid sealing resin 5 is simple.

  After the stabilization of the liquid surface of the liquid sealing resin 5 is confirmed, as shown in FIG. 10B, ultraviolet rays (hν) are irradiated from above through the glass plate 4 of the silicon microparticle structure 10, The liquid sealing resin 5 is cured.

  After the effect of the liquid sealing resin 5 is confirmed, the glass plate 4 that has become unnecessary is removed together with the spacer 3 for the net. When the molded product is taken out from the mold 21, the target silicon microparticle-lens composite structure 20 is obtained as shown in FIG.

  As described above, in FIG. 10, the production of the silicon microparticle-lens composite structure using the substantially spherical silicon microparticle (spherical silicon crystal) as a typical example of the semiconductor microparticle has been described. However, as described above, since the silicon fine particles may have other forms, a method of manufacturing a silicon fine particle-lens composite structure using teardrop type silicon fine particles will be described below. In addition, when teardrop type silicon micro-grains are used, each micro-grain has a square top with a sharp tip (hereinafter referred to as “corner”) and a bottom with a spherical surface on the opposite side (hereinafter referred to as “corner”). Therefore, when manufacturing silicon microparticles, the normal orientation method in which the corners of the silicon microparticles are embedded in a sealing resin and the spheres of the silicon microparticles are sealed. It is preferable to properly use two methods of the reverse orientation method of sealing in a form embedded in a stop resin. In the following, the present invention will be described with particular reference to silicon fine particles, but it goes without saying that the following method can also be used for other semiconductor fine particles.

Normal orientation method In the normal orientation method, after silicon micro-grains are arranged in advance on an array plate, each silicon micro-grain is supported by a companion support (made of an ultraviolet-transmissive plate-like member; Since it is used for transferring after being held, it is collectively moved to a transfer plate). The obtained support with silicon fine particles is used for the subsequent resin sealing step. Hereinafter, this normal orientation method will be described with reference to FIG.

  First, as shown in FIG. 11A, an array plate 43 and a support (transfer plate) 4 are prepared. The array plate 43 may be made of a metal material or a plastic material, but in this figure, a stainless steel (SUS) sheet having a thickness of 0.5 mm is used, and the corner portion of the silicon microparticle 1 is used. The fine holes 44 for temporarily fixing are opened by laser processing with a diameter of 0.7 mm and a pitch of 2 mm. The corners of the silicon microparticles 1 are inserted into the respective pores 44 as shown in the drawing, and are arranged so that the silicon microparticles 1 are substantially vertical. The silicon microparticles 1 are teardrop type silicon microparticles having a diameter of 1 mm, and sequentially have a silicon oxide film and an antireflection film on the surface thereof.

  The support 4 is made of a material capable of transmitting ultraviolet rays, and in this figure, a glass plate made of quartz glass having a thickness of 2 mm is used. A double-sided adhesive tape 41 is affixed to the lower surface (silicon fine particle holding surface) of the support 4 so as to cover a region corresponding to the position where the silicon fine particles are arranged. Further, (transfer spacers) 42 are fixed to both ends of the support 4. The height of the spacer 42 is such that when the support 4 is placed above the array plate 43, the distance from the top of the spherical portion of the silicon microparticles 1 disposed on the array plate 43 is 0.1 mm. It is the size which becomes a grade.

  Next, as shown in FIG. 11B, the array plate 43 and the support 4 are overlapped using a positioning jig 45 having a right angle between two or more sides thereof. Thereafter, while maintaining the positional relationship between the array plate 43, the support 4 and the alignment jig 45, the top and bottom are reversed as shown in FIG. As a result, the silicon microparticles 1 inserted into the pores 44 of the array plate 43 fall by gravity and are received by the double-sided adhesive tape 41 on the support 4 and are stably fixed.

  After fixing the silicon microparticles 1 on the support 4, the support 4 is taken out from the array plate 43 as shown in FIG. 11 (D), and then the spacer of the support 4 as shown in FIG. 11 (E). 42 is replaced with a curing spacer 3. In this way, a support 4 is obtained in which all the silicon microparticles 1 are arranged and held with the double-sided adhesive tape 41 having the same surface.

Inversion orientation method In the inversion orientation method, the array plate used in the normal orientation method is not used. That is, each silicon microparticle is held on a support (made of a plate member that is transparent to ultraviolet rays; it is also used to transfer after temporarily holding the silicon microparticle, so it is also called a transfer plate) , Used for the subsequent resin sealing step. Hereinafter, this inversion alignment method will be described with reference to FIG.

  First, as shown in FIG. 12 (A), a support 4 provided with pores 11 and fixing spacers 3 is prepared. The support 4 is made of a material capable of transmitting ultraviolet rays, and in this figure, a glass plate made of quartz glass having a thickness of 1 mm is used. The pores 11 are arranged in a staggered manner with a diameter of 0.7 mm and a pitch of 2 mm. The holes 11 were formed by laser processing (Io Laser).

  Next, as shown in FIG. 12B, after the grease 46 is thinly applied to the pores 11 of the support 4, the grease 46 is wiped cleanly so that only the pores 11 remain. As the grease, for example, a high-vacuum silicone grease (manufactured by Toray & Dow Corning) can be used.

  After the grease filling is completed, as shown in FIG. 12C, the corners of the silicon microparticles 1 are inserted into the pores 11 of the support 4 and fixed with the grease 46. All the silicon microparticles 1 are arranged with their spheres facing upward, and the support 4 is obtained.

  In the normal alignment method and the reverse alignment method described above, the support 4 provided with the silicon microparticles 1 with the corners or spheres facing upward is obtained. By using these supports 4, a silicon fine particle-lens composite structure can be manufactured as shown in FIG. 13 below. In the following description, the manufacture of the silicon microparticle-lens composite structure is used with reference to the support 4 derived from the normal orientation method, but the support 4 derived from the reverse orientation method is used. A silicon microparticle-lens composite structure can be manufactured by the same procedure.

  First, as shown in FIG. 13A, the support 4 with the silicon microparticles 1 described above with reference to FIG. 11E is prepared.

  Next, as shown in FIG. 13B, a mesh member 2 is prepared. The net-like member 2 used in this figure is an aluminum net (aluminum material: A1050, thickness 0.2 mm, line width 0.18 mm) in which regular hexagonal openings (mesh) are punched out. The mesh member 2 is provided with a spacer 13 (here, a plastic member is used) in order to fix the mesh member 2 to the support 1 with a predetermined interval.

  Next, on the surface of the support 4, a double-sided adhesive tape 41 is affixed to the site where the spacer 13 is affixed, and the mesh member 2 is fixed to that site. The mesh member 2 is arranged and fixed on the support 4 so that the silicon microparticles 1 are located in the center of each mesh. As a result, as shown in FIG. 13C, the mesh member 2 and the silicon microparticles 1 are arranged and fixed on the support body 4 without contact.

  After integrating the mesh member 2 and the support 4 with the silicon microparticles 1 as described above, the obtained integrated product is used as a gold for producing the silicon microparticle-lens composite structure shown in FIG. Align with the mold (lens mold) 21 and overlap. As shown in the drawing, the mold 21 is provided with a concave portion having a shape and a dimension corresponding to a target hemispherical lens body, and is formed by cutting stainless steel. The resin injection surface of the mold 21 is subjected to a release treatment by spraying a fluorine release material. Further, a plastic frame 22 for collecting a resin liquid is attached to the outer peripheral portion of the mold 21 with a double-sided adhesive tape so that the liquid resin does not leak to the periphery. A necessary amount of liquid sealing resin 5 is poured into the mold 21. The sealing resin 5 used here is an ultraviolet curable liquid resin.

  In aligning the support body 4 and the mold 21, for example, the mold 21 is fixed to a position adjustment jig (not shown) by contacting two or more sides, and the support body 4 is further attached to the position adjustment jig. In a state where two or more sides are combined, the support body 4 is lowered until the spacer 3 of the support body 4 comes into contact with the mold 21 disposed below. Thereby, the liquid surface of the liquid resin 5 is naturally formed between the adjacent silicon microparticles 1.

  After arranging the support 4, the mold 21 and the position adjusting jig as described above, it is introduced into the ultraviolet irradiation device while maintaining the positional relationship, and ultraviolet rays (hυ) are introduced as shown in FIG. ). As a result, the liquid resin 5 is cured, and as shown in FIG. 13F, the silicon fine particles 1 are oriented so that the corners of the silicon fine particles 1 face the lens surface, and a part of the silicon fine particles 1 is embedded in the resin 5. A silicon microparticle-lens composite structure 20 is obtained.

Furthermore, the present invention resides in a method for manufacturing a solar cell composed of a plurality of semiconductor microparticles each having a p-electrode and an n-electrode formed on each surface. The method for producing the solar cell of the present invention includes the following steps:
Disposing a plurality of semiconductor fine particles in a plane at a predetermined interval;
A net-like member having a plurality of openings arranged in a mesh shape is overlaid on the semiconductor fine particles, and the semiconductor fine particles are placed in respective openings of the net-like member at a position substantially at the center of the semiconductor fine particles. And forming a semiconductor fine grain structure arranged in a non-contact manner,
Contacting the curable resin in an uncured state with the resin-sealed portion of the semiconductor microparticle structure;
Forming a sealing member by curing the curable resin while maintaining a contact state between the semiconductor fine particle structure and the curable resin; and a p-electrode in a non-resin-sealed portion of the semiconductor fine particle And forming the n-electrode can be advantageously carried out by carrying out sequentially.

  FIG. 14 shows a preferred embodiment of the method for manufacturing a solar cell according to the present invention step by step. In this figure, for the sake of simplification of description, the semiconductor fine particle-lens composite structure starts from the point of completion. The semiconductor fine particle-lens composite structure used here is shown in FIG. Therefore, the semiconductor microparticle is a silicon microparticle having a diameter of about 1 mm.

  First, after the silicon microparticle-lens composite structure 10 is manufactured by the method shown in FIG. 10, a titanium oxide film that is an antireflection film on the surface with an acid mainly composed of dilute hydrofluoric acid, and a silicon oxide that is a protective film The film is removed to expose the n-layer Si. Next, as shown in FIG. 14A, an electrode material (for example, nickel, silver, etc.) is entirely deposited on the surface of the composite structure 10 opposite to the hemispherical lens body (condensing lens) 15. . For example, vacuum deposition is used as the deposition method. Further, the deposition may be performed in two or more times by masking. For example, nickel (Ni) is ideally deposited only on the silicon microparticles with a thickness of 30 nm, and then silver is deposited with a thickness of 2 μm on the entire surface including the resin surface. Thereby, it is possible to improve the reflection characteristics of the reflection surface. As a result, a reflective film 31 serving as an n-electrode, covering the exposed surface of the silicon microparticles 1 and the parabolic meniscus of the sealing resin, is obtained with a film thickness of about 2 μm.

  After the formation of the reflective film 31, a protective layer 32 is formed on the reflective film 31, as shown in FIG. The protective layer 32 is formed by, for example, applying an epoxy resin solution to one surface and curing it. The thickness of the protective layer 32 obtained is about 350 μm at the thickest place.

  Next, as shown in FIG. 14C, the already coated reflective film 31 and the protective layer 32 thereon are selectively removed from the upper surface of the silicon microparticles 1. For removal of these layers, for example, sandblasting and etching can be used. As a result, the n-electrode layer is removed, and the p-type Si layer on the surface of the silicon microparticles 1 is exposed.

  Subsequently, as shown in FIG. 14D, an insulating layer 33 is formed on all of the protective layer 32 and the upper surface of the silicon microparticle 1 not covered with the protective layer 32. The insulating layer 33 is formed by, for example, applying an epoxy resin solution to one surface and curing it. Since the insulating layer 33 also serves as a planarizing layer, the insulating layer 33 is formed with a film thickness such that the back surface of the obtained solar cell is a flat surface. The thickness of the insulating layer 33 obtained is about 100 μm.

  After the formation of the insulating layer 33, as shown in FIG. 14E, the upper surface of the silicon microparticles 1 is back-polished by, for example, chemical mechanical polishing (CMP), and the insulating layer 33 deposited in the previous step is formed. Selectively remove. As a result, the p-type Si layer on the surface of the silicon microparticle 1 is exposed again.

  After the above series of processing is completed, as shown in FIG. 14F, aluminum is vacuum-deposited on the entire back surface of the solar cell being manufactured, and a p-electrode layer having a thickness of about 1 μm is formed. Therefore, the silicon solar cell 30 having the configuration described above with reference to FIG. 8 is obtained.

  Subsequently, the present invention will be described with reference to examples thereof. Needless to say, the present invention is not limited to these examples.

Example 1
The molten silicon was freely dropped in an argon atmosphere from a height of about 15 m to produce teardrop type silicon fine particles (spherical silicon crystals) having a diameter of 1 mm. Next, an n layer was formed by phosphorus diffusion on the surface of the obtained silicon microparticles, and a silicon oxide film and an antireflection film were sequentially formed thereon.

  Further, a quartz glass glass plate (trade name “SK1300”; manufactured by Sumikin Ceramics Co., Ltd.) having a thickness of 1 mm was prepared, and pores having a diameter of 0.7 mm were formed on one side thereof in a staggered manner with a pitch of 2 mm. The drilling was performed by laser processing (Io Laser). In addition, when sealing a solar cell with silicon fine particles with a transparent UV curable resin, in order to form terminals, the silicon fine particles must be cast with a part of the silicon fine particles exposed. Silicon fine particles were formed in a pattern that could be densely packed on a plane at a pitch approximately twice the diameter. Next, high vacuum silicone grease (Toray & Dow Corning) was embedded in the pores of the glass plate.

Furthermore, in order to use as a mesh member, the following two types of metal nets each having a regular hexagonal opening were produced (see FIG. 3).
(1) Aluminum net Aluminum material (A1050), thickness 0.2 mm, line width 0.18 mm, a honeycomb structure with regular hexagonal openings is formed by punching by punching.
(2) Copper net After forming a honeycomb structure with a copper material (C1100-1 / 4H), a thickness of 0.2 mm, a line width of 0.18 mm, and a regular hexagonal opening by etching treatment, bright silver plating treatment.

  After preparing the silicon fine particles, the glass plate, and the aluminum and copper nets as described above, the corner portions of the silicon fine particles were inserted into the respective holes of the glass plate. Since the silicone grease was packed in the pores, each silicon fine particle was held on the glass plate.

  Next, an aluminum net or a copper net was attached to a glass plate with a double-sided adhesive tape and fixed. During this fixing operation, the net was set so that the hexagonal eyes of the net could be placed in contact with each silicon microparticle.

  After temporarily fixing the glass microparticles and the net to the glass plate as described above, the amount necessary for the recess of the silicon microparticle-lens composite structure mold (manufactured by Showa Seiko Co., Ltd.) prepared separately. The liquid sealing resin was added. The mold used here is made of stainless steel, and the spherical part corresponding to the lens part is formed by arranging hemispherical concave parts having a radius of 1.2 mm in a staggered manner with a pitch of 2 mm. “Fusoguard FC-109” (manufactured by Fine Chemical Japan Co., Ltd.) is applied. The liquid sealing resin used here was an ultraviolet curable acrylic resin (trade names “EXT055-5”, “LCR0631SC2”, and “LCR0632UV”; all manufactured by Toagosei Co., Ltd.).

  Subsequently, after aligning the mold and the glass plate, the glass plate was lowered toward the lower mold while paying attention so as not to shift the position. Even after the silicon fine particles contacted the liquid acrylic resin surface, the glass plate continued to be lowered while tension was applied, and when the set depth was reached, the descent of the glass plate was stopped. As described above with reference to FIG. 4, the free interface of the liquid acrylic resin was formed between the silicon fine particles and the net.

Then, the metal mold | die which mounted the glass plate was set to the ultraviolet irradiation apparatus (Brand name "ECS301-G1", the product made by an eye graphics company), and the liquid acrylic resin was hardened by irradiating an ultraviolet-ray from the glass plate side. The curing conditions were 3 to 6 J / cm ² of UV integrated light quantity.

  When the glass plate and the spacer 3 were removed and the obtained molded product was taken out of the mold, a silicon microparticle-lens composite structure having a cross-sectional profile as shown in FIG. 5 was obtained. In the obtained silicon microparticle-lens composite structure, the distance h from the apex p of the parabolic meniscus 16 to the upper end of the silicon microparticle 1 was 500 μm, and it was confirmed that a deep recess was formed. Further, in this composite structure, when the state of the net was observed from the lens side, the presence of the net itself could not be confirmed. In other words, this phenomenon confirms that the light reflected by the net works effectively toward the inside without going outside. It was also confirmed that power loss could be effectively reduced by passing current through an aluminum or copper net.

〔Evaluation test〕
A solar cell having the structure described above with reference to FIG. 9 was produced from the silicon microparticle-lens composite structure produced in this example.

  Next, the behavior of incident light in the vicinity of the silicon microparticles was simulated under the following conditions using a commercially available optical simulator (Light Tools, ver 5.0.0; Cybernet System), and the results shown in FIG. 15 were obtained. It was.

Lens radius: 1.2mm
Silicon sphere: true sphere (radius 0.5mm)
Center distance between silicon spheres (pitch): 2.0 mm
Lens partial resin refractive index: 1.46 (fixed for single wavelength irradiation)
Distance between lens surface curvature circle center and silicon sphere center (offset): 0.26 mm
Resin boundary line on the silicon surface (electrode forming line): 0.2 mm from the top of the silicon bottom
Irradiation light wavelength: 550 nm
Light source: A planar light source is used to reproduce parallel incidence; the illumination from the surface is uniform and the radiation density is constant.
In addition, since an actual solar cell is composed of a large number of lens-silicon sphere structure cells, an unspecified one was used for the simulation.

  Here, when the incident light is incident on the lens surface at an angle of 0 °, and the light beam is incident at an incident angle of 30 °, a large amount of the light beam reflected by the parabolic meniscus remains as it is. It was confirmed that it could be incident on. Also, from this result, the effective utilization rate of light at an incident angle of 30 ° is 221 when the following Comparative Example 1 is 100. Even when calculation was performed in increments of 10 ° from an incident angle of 0 ° to 80 °, and these were integrated, it was confirmed that the effective utilization factor of light in this example was 161 with the following Comparative Example 1 as 100. .

  Further, in the obtained solar cell, the relationship between the distance from the top of the silicon microparticles to the liquid surface of the sealing resin (acrylic resin: EXT055-5) and the thickness of the sealing resin non-adhered layer was plotted. The graph shown in FIG. In this test, a 0.2 mm aluminum net is used. In FIG. 17, the result of Comparative Example 1 is also shown for comparison. When comparing the result of Example 1 and the result of Comparative Example 1, in the case of Example 1 (with a net), the exposed position (non-attached layer thickness) is constant from the touchdown of the silicon microparticles, whereas In the case of Comparative Example 1 (without a net), the amount of subsidence changes. Since the magnitude of this change is greatly affected by the environment, it can be seen that the liquid level can be controlled more stably by using the net.

  Further, when the relationship between the net height and the sealing resin non-adhered layer thickness was plotted in the same solar cell, the graph shown in FIG. 18 was obtained. As can be understood from the results shown in the drawing, exposure position control when using a net can be easily performed by adjusting the net arrangement position, and there is a correlation between the height of the net and the exposure height. .

Comparative Example 1
Although description of the said Example 1 was repeated, in the case of this example, use of the net | network made from aluminum or copper was abbreviate | omitted for the comparison. When the obtained molded product was taken out from the mold, a silicon microparticle-lens composite structure having a cross-sectional profile as shown in FIG. 7 was obtained. In the obtained silicon microparticle-lens composite structure, it was confirmed that there was no parabolic meniscus as confirmed in Example 1, and a shallow concave portion having a depth of about 250 μm was formed.

〔Evaluation test〕
A solar cell having the structure described above with reference to FIG. 9 was produced from the silicon microparticle-lens composite structure produced in this example.

  Next, for the same solar cell, the amount of received light was evaluated by an optical simulator by the same method as in Example 1, and the result shown in FIG. 16 was obtained. From the obtained results, when the net is not used, the light reflected by the non-meniscus liquid surface is repeatedly reflected in the lens body, and only a very small amount of light is incident on the semiconductor microparticles. It was confirmed that the light beam was emitted from the lens body.

  Moreover, in the obtained solar cell, when the relationship between the distance from the spherical top of the semiconductor fine particles to the sealing resin liquid surface and the thickness of the sealing resin non-adhered layer was plotted, the graph shown in FIG. 17 was obtained. As described above with reference to FIG. 17, in the case of this example, it can be seen that the amount of sinking is undesirably changed.

It is sectional drawing which showed the preferable one form of the semiconductor fine grain structure by this invention. It is sectional drawing which showed one preferable form of the semiconductor fine particle-lens composite structure by this invention. It is the enlarged photograph which showed an example of the net-like member used in the semiconductor fine particle-lens composite structure of this invention. In the semiconductor fine particle-lens composite structure of this invention, it is the enlarged photograph which showed the state by which the semiconductor fine particle was arrange | positioned non-contactingly at the opening part of the mesh member. In the semiconductor fine particle-lens composite structure of this invention, it is sectional drawing which showed the liquid level profile of sealing resin in the semiconductor fine particle vicinity. In the semiconductor fine particle-lens composite structure of this invention, it is an enlarged photograph (100 times) which showed the liquid level profile in the semiconductor fine particle vicinity of the cast liquid sealing resin. It is sectional drawing which showed the liquid level profile of sealing resin in the semiconductor microparticle vicinity in the semiconductor microparticle-lens composite structure produced without using a net-like member for the comparison. It is an enlarged photograph (100 times) which showed the liquid level profile in the semiconductor fine particle vicinity of the cast liquid sealing resin in the semiconductor fine particle-lens composite structure produced without using a net-like member for comparison. It is sectional drawing which showed one preferable form of the solar cell (part) by this invention. It is sectional drawing which showed order for an example of the manufacturing method of the semiconductor fine particle-lens composite structure by this invention later on. It is sectional drawing which showed order for an example of the manufacturing method of the semiconductor fine grain structure by this invention later on. It is sectional drawing which showed order for another example of the manufacturing method of the semiconductor fine grain structure by this invention later on. It is sectional drawing which showed the method of manufacturing the semiconductor microparticle-lens composite structure of this invention using the semiconductor microparticle structure manufactured by the method of FIG. 11 in order. It is sectional drawing which showed an example of the manufacturing method of the solar cell by this invention later on. In the solar cell of this invention, it is a light ray figure which shows the result of having simulated the behavior of the incident light in the semiconductor fine particle vicinity. It is a ray diagram which shows the result of having simulated the behavior of the incident light in the semiconductor microparticle vicinity in the solar cell produced without using a net-like member for the comparison. In the solar cell of this invention, it is the graph which plotted the relationship between the distance from the spherical top of a semiconductor fine particle to sealing resin liquid level, and sealing resin non-adhesion layer thickness. In the solar cell of this invention, it is the graph which plotted the relationship between the height of a mesh-like member, and sealing resin non-adhesion layer thickness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor microparticle 2 Reticulated member 3 Spacer 4 Support body 5 Sealing member 10 Semiconductor microparticle structure 12 Opening part 13 Bonding material 15 Hemispherical lens body 16 Parabolic meniscus 20 Semiconductor microparticle-lens composite structure 21 Mold 30 Solar cell 31 Reflective film 32 Protective layer 33 Insulating layer 34 Electrode layer

Claims (22)

A plurality of semiconductor microparticles arranged in a plane at predetermined intervals;
A plurality of openings arranged in a mesh shape, and the semiconductor fine particles arranged in the respective openings at a substantially central position of the semiconductor fine particles and in a non-contact manner;
A semiconductor fine grain structure comprising:   2. The semiconductor microparticle structure according to claim 1, wherein the semiconductor microparticle is a microsphere in the form of a true sphere, a distorted sphere, or a teardrop, or a microparticle in the form of a cube or a rectangular parallelepiped.   The semiconductor fine particle structure according to claim 1, wherein the semiconductor fine particles are silicon fine particles.   The semiconductor fine particle structure according to any one of claims 1 to 3, wherein the semiconductor fine particles are formed by free-falling a molten semiconductor material by gravity.   The semiconductor fine particle structure according to any one of claims 1 to 4, wherein the semiconductor fine particles are not mechanically polished.   6. The mesh member according to claim 1, wherein the openings are arranged in regular rows and columns, and the semiconductor fine particles are located substantially at the center of each opening. The semiconductor fine grain structure according to any one of the above.   The said net-like member WHEREIN: The said opening part has a circular, rectangular, triangular, hexagonal shape, or a polygonal opening pattern rather than it, The any one of Claims 1-6 characterized by the above-mentioned. Semiconductor fine grain structure.   The semiconductor fine grain structure according to claim 1, wherein the mesh member is made of a conductive material.   The semiconductor fine grain structure according to claim 1, wherein at least a surface of the mesh member is provided with light reflectivity.   The wetness with respect to the resin used for sealing of the said net-like member and the said semiconductor fine particle is controlled at least in the opening part of the said net-like member, The any one of Claims 1-9 characterized by the above-mentioned. The semiconductor fine grain structure described.   The semiconductor fine particle structure according to claim 1, further comprising a support body that temporarily holds the semiconductor fine particles and the mesh member. The semiconductor fine grain structure according to any one of claims 1 to 10,
A sealing member made of a light-transmitting resin that seals the first region occupying almost half of the outer peripheral surface of the semiconductor fine particles and the mesh member,
Sealing the first region of the semiconductor microparticles with a predetermined thickness to form a hemispherical lens body;
In the second region of the semiconductor microparticle opposite to the first region, the outer peripheral surface of the semiconductor microparticle is exposed, and the mesh member is apex between the adjacent semiconductor microparticles. And a sealing member in which the parabolic meniscus is formed by the surface tension of the resin.   13. The semiconductor fine particle-lens composite structure according to claim 12, wherein the parabolic meniscus pattern and the depth thereof are controlled by the mesh member and the semiconductor fine particles.   The said 2nd area | region has further the reflecting film which coat | covered the outer peripheral surface of the said semiconductor microparticle, and the surface of the said sealing member adjacent to the said semiconductor microparticle. The semiconductor fine particle-lens composite structure described.   15. A semiconductor device comprising the semiconductor fine particle-lens composite structure according to claim 12.   16. The semiconductor device according to claim 15, wherein the semiconductor device is a solar cell, and a p-electrode and an n-electrode are formed on each surface of the semiconductor fine particles. A method of encapsulating a plurality of semiconductor fine particles in a lump with the following steps:
Disposing a plurality of semiconductor fine particles in a plane at a predetermined interval;
A net-like member having a plurality of openings arranged in a mesh shape is overlaid on the semiconductor fine particles, and the semiconductor fine particles are placed in respective openings of the net-like member at a position substantially at the center of the semiconductor fine particles. And forming a semiconductor fine grain structure arranged in a non-contact manner,
In a state where the curable resin is brought into contact with the portion to be resin-sealed of the semiconductor fine particle structure in an uncured state, and in a state where the contact state between the semiconductor fine particle structure and the curable resin is maintained, A resin sealing method comprising curing a curable resin to form a resin sealing member.   The resin sealing method according to claim 17, wherein the curable resin is a thermosetting resin or a photocurable resin.   The resin sealing method according to claim 17 or 18, wherein, in the resin contact step, the semiconductor fine grain structure is pushed into a mold including the curable resin.   In the resin curing step, a hemispherical lens body formed from a resin in which a first region occupying almost half of the outer peripheral surface of the semiconductor microparticles is sealed with a predetermined thickness, and the semiconductor microparticles adjacent to each other 21. A resin sealing member comprising a parabolic meniscus formed by a surface tension of the resin and having the mesh member as a vertex is formed between the resin sealing member and the resin sealing member. The resin sealing method described in 1. A method for producing a solar cell comprising a plurality of semiconductor fine particles having a p-electrode and an n-electrode formed on each surface, the following steps:
Disposing a plurality of semiconductor fine particles in a plane at a predetermined interval;
A net-like member having a plurality of openings arranged in a mesh shape is overlaid on the semiconductor fine particles, and the semiconductor fine particles are placed in respective openings of the net-like member at a position substantially at the center of the semiconductor fine particles. And forming a semiconductor fine grain structure arranged in a non-contact manner,
Contacting the curable resin in an uncured state with the resin-sealed portion of the semiconductor microparticle structure;
Forming a resin sealing member by curing the curable resin while maintaining a contact state between the semiconductor fine particle structure and the curable resin; and p in the non-resin sealing portion of the semiconductor fine particle. A method of manufacturing a solar cell, comprising forming an electrode and an n-electrode.   The method for manufacturing a solar cell according to claim 21, wherein the semiconductor fine particles are silicon fine particles formed by free-fall of molten silicon.