JP2012234994A - Semiconductor silicon film and semiconductor device, and method for manufacturing them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new semiconductor silicon film and a semiconductor device having such a semiconductor silicon film, and a method for manufacturing them.SOLUTION: A semiconductor silicon film (160) is a semiconductor silicon film in which a plurality of thin and long silicon particles (22) are adjoined with each other in a short axis direction, here, the thin and long silicon particles (22) are a sintered body of the plurality of the silicon particles. The method for manufacturing such a semiconductor silicon film (160) includes the steps of: applying a first silicon particle dispersion onto a substrate (100), drying the applied first silicon particle dispersion, irradiating the dried first silicon particle dispersion with light (200) to form a first semiconductor silicon film (130); and applying a second silicon particle dispersion onto the first semiconductor silicon film (130), drying the applied second silicon particle dispersion, and irradiating the dried second silicon particle dispersion with the light (200). In the method, the dispersion of the first silicon particles in the first silicon particle dispersion is 5 nmor more.

Description

  The present invention relates to a novel semiconductor silicon film, a semiconductor device having such a semiconductor silicon film, and a manufacturing method thereof.

  Semiconductor silicon films, such as amorphous silicon films and polysilicon films, are used for semiconductor devices such as thin film transistors (TFTs) and thin film solar cells.

  When such a semiconductor silicon film is used in a semiconductor device, the semiconductor silicon film is subjected to vacuum processes such as physical vapor deposition (PVD) such as sputtering and chemical vapor deposition (CVD) such as plasma chemical vapor deposition. Has been formed on the entire surface of the substrate. In addition, when it is necessary for the semiconductor silicon film to have a desired pattern, for example, a circuit pattern, unnecessary portions of the semiconductor silicon film formed on the entire surface of the base material are removed by photolithography or the like so that the desired pattern is obtained. It has been performed to provide a semiconductor silicon film having the same.

  However, in these conventional methods, a large-scale apparatus is required, a large amount of energy is consumed, and since the process temperature is high (over 250 ° C.), it takes a lot of time for cooling for each process, Since the raw material is a gas, it has problems such as difficulty in handling and generation of a large amount of waste, which makes it a complicated and expensive method. In particular, when it is necessary for the semiconductor silicon film to have a desired pattern, unnecessary portions of the semiconductor silicon film formed on the entire surface of the base material are removed, so that the use efficiency of the raw material is poor (less than 5%). Was also a problem.

  Therefore, in recent years, a liquid phase method has been studied as a method for forming a semiconductor film for a thin film transistor or the like at a relatively low temperature. In the liquid phase process, the entire process can generally be performed at a relatively low temperature, for example, a temperature below the glass transition temperature of the polymer material. In such a low-temperature process, an inexpensive general-purpose polymer material can be used as a base material for a semiconductor film, and thereby, an increase in area, flexibility, weight reduction, and cost reduction of a semiconductor device can be expected. Further, in such a low temperature process, the process time can be shortened because cooling for each process is not necessary.

  Regarding the production of a semiconductor film by such a liquid phase method, the use of an organic semiconductor material has been studied.

  However, the organic semiconductor film has insufficient performance such as carrier mobility and durability such as stability in the atmosphere as compared with the silicon semiconductor film. It is difficult to make it easier.

  In addition, regarding the production of a semiconductor film using a liquid phase method, the use of an inorganic compound semiconductor material has been studied.

In this regard, for example, Patent Document 1 discloses a method of forming an InGaZnO ₄ film using a nanoparticle dispersion. In Patent Document 1, an InGaZnO ₄ film dried at room temperature is pretreated with an ultraviolet (UV) ozone cleaner, and then irradiated with a KrF excimer laser (wavelength: 248 nm), whereby a relatively uniform InGaZnO ₄ film is formed. A crystal film is formed. In Patent Document 1, a thin film transistor having a carrier mobility of 1.2 cm ² / V · s is manufactured by such a method.

However, inorganic compound semiconductor materials such as InGaZnO ₄ are very expensive compared to silicon semiconductors due to the problem of raw material availability, and are not practical as general TFT materials.

  Further, regarding the production of a semiconductor film using a liquid phase method, it has been studied to produce a semiconductor polysilicon film using an organic silicon compound solution, for example, a silicon solution containing a hydrogenated cyclic silane compound.

  In this regard, for example, Patent Documents 2 and 3 use an organic silicon compound solution containing a high molecular weight low-volatile polysilane compound. Here, this low volatility polysilane compound is obtained using cyclopentasilane as a precursor.

  However, in the case of an organosilicon compound solution, it may be necessary to perform a dehydrogenation annealing process (400 to 500 ° C.) in order to reduce explosive properties, and thus it is difficult to lower the temperature of the entire process.

  Patent Document 4 proposes forming a semiconductor silicon film by using a dispersion containing silicon particles.

  Regarding the use of the liquid phase method, it is also considered to use a direct drawing technique for directly drawing a desired pattern of a semiconductor silicon film on a substrate. Examples of the direct drawing technique include a printing method in which a raw material liquid containing a constituent material of a semiconductor silicon film is applied and printed, such as an ink jet printing method and a screen printing method.

  In such a printing method, a vacuum process is unnecessary, and pattern formation can be performed by direct drawing, so that a semiconductor device can be manufactured easily and at low cost.

  As silicon films, films having various forms have been proposed. For example, in Patent Document 5, a semiconductor silicon film having columnar crystal grains adjacent to each other in the minor axis direction is manufactured by a vapor phase method. Has proposed.

JP 2009-147192 A JP 2004-87546 A (corresponding to Patent 4016419) Special table 2010-506001 Special table 2010-514585 gazette JP 2002-270511 A

  An object of the present invention is to provide a novel semiconductor silicon film, a semiconductor device having such a semiconductor silicon film, and a manufacturing method thereof.

As a result of intensive studies, the present inventor has arrived at the present invention described below.
<1> A semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the minor axis direction, wherein the elongated silicon particles are a sintered body of a plurality of silicon particles.
<2> The semiconductor silicon film according to <1>, wherein at least a part of the elongated silicon particles has a minor axis diameter of 100 nm or more.
<3> The semiconductor silicon film according to <1> or <2>, wherein at least a part of the elongated silicon particles has an aspect ratio of more than 1.2.
<4> A semiconductor device having the semiconductor silicon film according to any one of <1> to <3>.
<5> The semiconductor device according to <4>, which is a solar cell.
<6> A method for producing a semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the minor axis direction,
(A) A first silicon particle dispersion containing a first dispersion medium and first silicon particles dispersed in the first dispersion medium is applied onto a substrate, and the first silicon is dispersed. Forming a particle dispersion film;
(B) drying the first silicon particle dispersion film to form a first unsintered semiconductor silicon film; and (c) irradiating the first unsintered semiconductor silicon film with light. Sintering the first silicon particles in the first unsintered semiconductor silicon film, thereby forming a first semiconductor silicon film,
(D) applying a second silicon particle dispersion containing the second dispersion medium and the second silicon particles dispersed in the second dispersion medium to the first semiconductor silicon film; Forming a second silicon particle dispersion film;
(E) drying the second silicon particle dispersion film to form a second unsintered semiconductor silicon film; and (f) irradiating the second unsintered semiconductor silicon film with light. And sintering the second silicon particles in the second unsintered semiconductor silicon film,
And the dispersion of the first silicon particles is 5 nm ² or more.
<7> The method according to <6> above, wherein the average primary particle diameter of the silicon particles is 100 nm or less.
<8> The method according to <6> or <7>, wherein the silicon particles are silicon particles obtained by a laser pyrolysis method.
<9> The method according to any one of <6> to <8>, wherein the unsintered semiconductor silicon film has a thickness of 50 to 2000 nm.
<10> The method according to any one of <6> to <9>, wherein the light irradiation is performed using a laser.
<11> The method according to any one of <6> to <10>, wherein the light irradiation is performed in a non-oxidizing atmosphere.
<12> A semiconductor silicon film obtained by the method according to any one of <6> to <11> above.
<13> A method for producing a semiconductor device, comprising producing a semiconductor silicon film by the method according to any one of <6> to <11> above.
<14> A semiconductor device obtained by the method according to <13>.

  According to the semiconductor silicon film of the present invention in which a plurality of elongated silicon particles are adjacent to each other in the minor axis direction, good carrier mobility can be achieved in a device in which carriers flow in the thickness direction of the semiconductor silicon film. This is because such a semiconductor silicon film has few grain boundaries or substantially no grain boundaries in the thickness direction of the semiconductor silicon film, that is, the major axis direction of the elongated silicon particles. Moreover, according to the method of the present invention for producing a semiconductor silicon film, the semiconductor silicon film of the present invention can be obtained by a liquid phase method.

FIG. 1 is a diagram for explaining the method of the present invention for producing a semiconductor silicon film. 2 is a field emission scanning electron microscope (FE-SEM) photograph of the semiconductor silicon film of Example 1. FIG. Here, FIG. 2A is a photograph of a side section observed from obliquely above, and FIG. 2B is a photograph of the side section observed from the side. FIG. 3 is a diagram showing the configuration of the solar cell created in Example 1. FIG. 4 is a graph showing current-voltage (IV) characteristics of the solar cell created in Example 1. FIG. 5 is a field emission scanning electron microscope (FE-SEM) photograph of the semiconductor silicon film of Reference Example 1. Here, Fig.5 (a) is the photograph which observed the side surface cross section from diagonally upward, and FIG.5 (b) is the photograph which observed the side surface cross section from right side. 6 is a field emission scanning electron microscope (FE-SEM) photograph of the semiconductor silicon film of Reference Example 2. FIG. Here, FIG. 6 is a photograph of the side cross section observed from the side.

<Semiconductor silicon film>
The semiconductor silicon film of the present invention is a semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the minor axis direction. Here, the elongated silicon particles of the semiconductor silicon film of the present invention are a sintered body of a plurality of silicon particles.

(Short shaft diameter)
At least a part of the elongated silicon particles can have a minor axis diameter of 100 nm or more, or 200 nm or more. The minor axis diameter may be 1,000 nm or less, 800 nm or less, or 500 nm or less. Here, “at least a part of the elongated silicon particles” may be, for example, at least 10% or more, 20% or more, 30% or more, 40% or more, or 50% or more of the elongated silicon particles based on the number.

  When the short axis diameter of the elongated silicon particles is too small, that is, when the elongated silicon particles are too small, the grain boundary in the semiconductor silicon film becomes too large, and thus good carrier mobility may not be achieved. In addition, if the minor axis diameter is too large, that is, if the elongated silicon particles are too large, the structure of the semiconductor silicon film becomes rough, and thereby good carrier mobility may not be achieved.

(aspect ratio)
At least a portion of the elongated silicon particles can have an aspect ratio greater than 1.0, greater than 1.2, or greater than 1.5. The aspect ratio may be 5.0 or less, 4.0 or less, or 3.0 or less. Here, “at least a portion of the elongated silicon particles” may be, for example, at least 10%, 20%, 30%, 40%, or 50% of the elongated silicon particles based on the number.

  When the aspect ratio of the elongated silicon particles is too small, the effect of the present invention that good carrier mobility can be achieved in a device that allows carriers to flow in the thickness direction of the semiconductor silicon film is reduced. In addition, when the aspect ratio is too large, the unevenness of the film surface becomes large, which may cause the film structure to be non-uniform.

(Production method)
The method for producing the semiconductor silicon film of the present invention is not particularly limited. For example, the semiconductor silicon film can be obtained by the method of the present invention. For details of each component, see the description relating to the method of the present invention for producing a semiconductor silicon film. it can.

<Semiconductor device>
The semiconductor device of the present invention has the semiconductor silicon film of the present invention as a semiconductor film. The semiconductor device of the present invention may be, for example, a field effect transistor or a solar cell.

<< Semiconductor Silicon Film Manufacturing Method >>
The method of the present invention for producing a semiconductor silicon film having a substrate and a semiconductor silicon film laminated on the substrate includes the following steps (a) to (f):
(A) A first silicon particle dispersion containing a first dispersion medium and a first silicon particle dispersion containing first silicon particles dispersed in the first dispersion medium is applied onto a substrate, and the first silicon particles Forming a dispersion film;
(B) drying the first silicon particle dispersion film to form a first unsintered semiconductor silicon film; and (c) irradiating the first unsintered semiconductor silicon film with light; Sintering the first silicon particles in the first unsintered semiconductor silicon film, thereby forming the first semiconductor silicon film;
(D) applying a second silicon particle dispersion containing the second dispersion medium and the second silicon particles dispersed in the second dispersion medium to the first semiconductor silicon film; Forming a silicon particle dispersion film of
(E) drying the second silicon particle dispersion film to form a second unsintered semiconductor silicon film, and (f) irradiating the second unsintered semiconductor silicon film with light, Sintering the second silicon particles in the second unsintered semiconductor silicon film.

  Here, in the method of the present invention, the dispersion of the first silicon particles is 5 or more.

  As described above, in the method of the present invention, after the first semiconductor silicon film is formed from the first silicon particle dispersion in steps (a) to (c), the steps (d) to (f) are further performed. A second silicon particle dispersion is applied onto the first semiconductor silicon film, dried, and sintered to form a second semiconductor silicon film. According to such a method of the present invention, a semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the minor axis direction can be obtained.

  Although not limited to the principle, this is considered to be due to the following reasons. That is, the first semiconductor silicon film has a plurality of sintered silicon particles scattered on the base material, and the second silicon particles grow using the sintered silicon particles as nuclei. Here, although the grain growth of the second silicon particles can occur both in the vertical direction and in the horizontal direction with respect to the base material, the grain growth in the horizontal direction is based on other adjacent sintered silicon particles. Since it is limited by the grains, it is considered that the grain growth in the vertical direction becomes relatively large.

  Specifically, for example, the method of the present invention can be performed as shown in FIG.

That is, in the step (a) of the method of the present invention, as shown in FIG. 1 (1), the first silicon particle dispersion containing the first dispersion medium (15) and the first silicon particles (10). Is applied onto the substrate (100) to form the first silicon particle dispersion film (110). Here, the dispersion of the first silicon particles is 5 nm ² or more. That is, the first silicon particles have a relatively large particle size distribution.

  In step (b), as shown in FIG. 1 (2), the first silicon particle dispersion film (110) is dried to form a first unsintered semiconductor silicon film (120).

  In step (c), as shown in FIG. 1 (3), the first unsintered semiconductor silicon film (120) is irradiated with light (200) to sinter the first silicon particles (10). Thereby forming a first semiconductor silicon film (130) having sintered silicon particles (12). Here, as described above, since the particle size distribution of the first silicon particles is relatively large, relatively small silicon particles are sintered around the relatively large silicon particles as a nucleus, and thereby the first silicon particles are sintered. One semiconductor silicon film is not a flat film but a film composed of a plurality of sintered silicon particles.

  In the step (d), as shown in FIG. 1 (4), the second silicon particle dispersion containing the second dispersion medium (25) and the second silicon particles (20) is converted into the first semiconductor silicon film. (130) to form a second silicon particle dispersion film (140).

  In step (e), as shown in FIG. 1 (5), the second silicon particle dispersion film (140) is dried to form a second unsintered semiconductor silicon film (150).

  In step (f), as shown in FIG. 1 (6), the second unsintered semiconductor silicon film (150) is irradiated with light (200) to sinter the second silicon particles (20). Thereby, a semiconductor silicon film (160) having elongated silicon particles (22) is formed.

<< Semiconductor Silicon Film Manufacturing Method-Steps (a) and (d) >>
In steps (a) and (d) of the method of the present invention, a silicon particle dispersion containing a dispersion medium and silicon particles dispersed in the dispersion medium is applied onto a substrate, and the silicon particle dispersion A film is formed.

(Dispersion medium)
The dispersion medium of the silicon particle dispersion is not limited as long as the object and effect of the present invention are not impaired. Therefore, for example, an organic solvent that does not react with silicon particles can be used. Specifically, this dispersion medium is a non-aqueous solvent such as alcohol, alkane, alkene, alkyne, ketone, ether, ester, aromatic compound, or nitrogen-containing ring compound, particularly isopropyl alcohol (IPA), N-methyl-2. -It may be pyrrolidone (NMP) or the like. Moreover, glycol (dihydric alcohol) like ethylene glycol can also be used as alcohol. The dispersion medium is preferably a dehydrated solvent in order to suppress oxidation of silicon particles.

(Silicon particles)
The dispersion of the first silicon particles is 5 nm ² or more, 10 nm ² or more, 20 nm ² or more, or 30 nm ² or more. Further, this dispersion may be 200 nm ² or less, 100 nm ² or less, or 80 nm ² or less.

  If the dispersion of the first silicon particles is too small, the silicon particles are uniformly sintered when sintered by light, and tend to form a relatively flat film. When such a flat film is used as the first semiconductor silicon film in the method of the present invention, a semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the short axis direction cannot be finally obtained. Sometimes. Also, if the dispersion of the first silicon particles is too large, the non-uniformity of the resulting film will be too great when sintered by light, and thereby the non-uniformity of the final film will be too great. There is.

Further, the dispersion of the second silicon particles is not particularly limited, but is, for example, 5 nm ² or more, 10 nm ² or more, 20 nm ² or more, or 30 nm ² or more. Further, this dispersion may be 200 nm ² or less, 100 nm ² or less, or 80 nm ² or less.

The silicon particle dispersion (σ ² ) is a value obtained by the following equation when the minor axis diameter of each particle is x ₁ , x ₂ , x ₃ ,..., X _n :

The silicon particles of the silicon particle dispersion are not limited as long as the objects and effects of the present invention are not impaired. For example, silicon particles as shown in Patent Document 4 can be used. Specifically, examples of the silicon particles include silicon particles obtained by a laser pyrolysis method, particularly a laser pyrolysis method using a CO ₂ laser.

  The silicon particles may be silicon particles comprising a polycrystalline or single crystal core and an amorphous outer layer. In this case, a combination of semiconductor characteristics with a polycrystalline or single crystal core and ease of sintering with an amorphous outer layer can be utilized.

  The silicon particles preferably have an average primary particle diameter of 100 nm or less. Accordingly, the silicon particles may be, for example, 1 nm or more, or 5 nm or more, and 100 nm or less, 50 nm or less, or 30 nm or less. An average primary particle size of 100 nm or less is preferable in order to sinter silicon particles with light.

  Here, in the present invention, the average primary particle diameter of the particles is obtained by directly measuring the particle diameter based on a photographed image by observation with a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like. The number average primary particle diameter can be obtained by measuring and analyzing a particle group consisting of 100 or more aggregates.

  The silicon particle dispersion used in the method of the present invention may contain a dopant such as phosphorus and boron and known additives in addition to the dispersion medium and silicon particles.

(Base material)
The base material used by the method of this invention is not restrict | limited unless the objective and effect of this invention are impaired. Therefore, for example, a silicon substrate can be used as the substrate.

  However, in the method of the present invention, since a semiconductor silicon film can be formed on a substrate at a relatively low temperature, a substrate having a relatively low heat resistance, for example, a substrate having a polymer material can be used. As the base material having a polymer material, a base material made of a polymer material having a conductive film or a semiconductor film provided on the surface can be used. Here, the conductive film may be a film of a metal, a metal oxide, particularly a transparent conductive oxide such as indium zinc oxide (IZO) or indium tin oxide (ITO). The semiconductor film may be a semiconductor silicon film.

  Since the production method of the present invention can be performed by a low temperature process, the polymer material for the substrate has a glass transition temperature of 300 ° C. or lower, 250 ° C. or lower, 200 ° C. or lower, 100 ° C. or lower, or 50 ° C. or lower. A polymeric material can be used.

  Therefore, for example, as the polymer material, a polymer material containing at least one selected from the group consisting of polyimide, polyethersulfone, polycarbonate, polyethylene terephthalate, and polyethylene naphthalate can be used. Among these, a polymer material containing at least one selected from the group consisting of polycarbonate, polyethylene terephthalate and polyethylene naphthalate, particularly a polymer material containing 50% by mass or more of polycarbonate, these polymers are versatile. And, it is preferable in that it is inexpensive.

(Application)
Application of the silicon particle dispersion is not particularly limited as long as the silicon particle dispersion can be applied with a desired thickness and uniformity, and can be performed by, for example, an inkjet method, a spin coating method, or the like.

  Further, in this coating, the thickness of the unsintered semiconductor silicon film obtained when the silicon particle dispersion film is dried is 50 nm or more, 100 nm or more, or 200 nm or more, and is 2000 nm or less, 1000 nm or less, 500 nm or less. Or 300 nm or less.

  Specifically, for example, when a field effect transistor (FET) is obtained, coating is performed so that the thickness of the unsintered semiconductor silicon film is 50 nm or more and 100 nm or more, and 500 nm or less and 300 nm or less. be able to. Moreover, when obtaining a solar cell, it coat | covers so that the thickness of a non-sintered semiconductor silicon film may be 100 nm or more and 200 nm or more, and is 2000 nm or less, 1000 nm or less, 500 nm or less, or 300 nm or less. Can do.

<< Semiconductor Silicon Film Manufacturing Method-Steps (b) and (e) >>
In steps (b) and (e) of the method of the present invention, the silicon particle dispersion film is dried to form an unsintered semiconductor silicon film.

(Dry)
This drying is not particularly limited as long as the dispersion medium can be substantially removed from the silicon particle dispersion film. For example, the drying is performed by placing a substrate having the silicon particle dispersion film on a hot plate. be able to.

  The drying temperature can be selected, for example, so as not to deform or deteriorate the substrate, for example, 50 ° C or higher, 70 ° C or higher, 90 ° C or higher, and 100 ° C or lower, 150 ° C or lower, 200 ° C or lower, or It can be selected to be 250 ° C. or lower.

  This drying can also be performed as an integrated process with the application of the steps (a) and (d). For example, the application of the steps (a) and (d) is performed by spin coating, and the application and the drying are simultaneously performed. You can also. That is, the drying is performed only as a process integrated with the application, and may not be performed as a separate process from the application.

<< Semiconductor Silicon Film Manufacturing Method-Steps (c) and (f) >>
In step (c) of the method of the present invention, the unsintered semiconductor silicon film is irradiated with light to sinter silicon particles in the unsintered semiconductor silicon film, thereby forming a semiconductor silicon film.

(Irradiated light)
As the light irradiated here, any light can be used as long as the sintering of the silicon particles in the unsintered semiconductor silicon film can be achieved, for example, laser light, particularly a wavelength of 600 nm or less, 500 nm or less, or 400 nm or less. Thus, it can be performed using a laser of 300 nm or more. The sintering of the silicon particles can also be performed using a flash lamp such as a xenon flash lamp.

When irradiation is performed using pulsed light having a relatively short wavelength (for example, a YVO laser having a wavelength of 355 nm), the number of irradiations of the pulsed light is, for example, 1 or more, 2 or more, 5 or more, or 10 times. It is above, It can be made 100 times or less, 80 times or less, or 50 times or less. In this case, the irradiation energy of the pulsed light, for ^{example, 15mJ / (cm 2 · shot} ) ^{above, 50mJ / (cm 2 · shot} ) ^{above, 100mJ / (cm 2 · shot} ) above, 150 mJ / (cm ² -Shot) or more, or 200 mJ / (cm ² · shot) or more, 800 mJ / (cm ² · shot) or less, 500 mJ / (cm ² · shot) or less, 300 mJ / (cm ² · shot) or less, or 250 mJ / (cm ² · shot) or less. Further, in this case, the irradiation time of the pulsed light can be set to, for example, 200 nanoseconds / shot or less, 100 nanoseconds / shot or less, and 50 nanoseconds / shot or less.

In addition, when irradiation is performed using pulsed light having a relatively long wavelength (for example, a green laser having a wavelength of 532 nm), the number of irradiation times of the pulsed light is, for example, 5 times or more, 10 times or more, 25 times or more, or It can be 50 times or more and 300 times or less, 200 times or less, or 100 times or less. In this case, the irradiation energy of the pulsed light, for ^{example, 100mJ / (cm 2 · shot} ) ^{above, 300mJ / (cm 2 · shot} ) ^{above, 500mJ / (cm 2 · shot} ) above, 900 mJ / (cm ² · shot) or more, or 1300 mJ ^/ (a in cm 2 · shot) ^{above, 3000mJ / (cm 2 · shot} ) or ^{less, 2000mJ / (cm 2 · shot} ) or less, or 1500mJ ^/ (cm 2 · shot) below can do. In this case, the irradiation time of the pulsed light is, for example, 50 nanoseconds / shot or more, 100 nanoseconds / shot or more, or 150 nanoseconds / shot or more, and 300 nanoseconds / shot or less, 200 nanoseconds. Seconds / shot or less, or 180 nanoseconds / shot or less.

  Here, if the number of times of light irradiation is too small, the energy per one pulse required to achieve the desired sintering is increased, and therefore the semiconductor silicon film may be damaged. Moreover, when the frequency | count of light irradiation is too many, there exists a possibility that the processing time required may become excessively long.

  In addition, as described above, selecting the number of times of irradiation with pulsed light, irradiation energy, and irradiation time can reduce silicon particles while suppressing deterioration of the polymer material due to heat, particularly when the base material has a polymer material. It may be preferable to achieve sintering.

(Irradiation atmosphere)
The light irradiation for sintering the silicon particles is preferably performed in a non-oxidizing atmosphere, for example, an atmosphere including hydrogen, a rare gas, nitrogen, and a combination thereof in order to prevent oxidation of the silicon particles. Here, examples of the rare gas include argon, helium, and neon. Note that it is preferable that the atmosphere contains hydrogen in order to suppress oxidation of silicon particles of the unsintered semiconductor silicon film. In order to obtain a non-oxidizing atmosphere, the oxygen content of the atmosphere can be 1% by volume or less, 0.5% by volume or less, 0.1% by volume or less, or 0.01% by volume or less.

<< Semiconductor Device Manufacturing Method >>
The inventive method of manufacturing a semiconductor device, such as a field effect transistor (FET) or solar cell, includes the step of making a semiconductor silicon film by the inventive method. For example, the method of the present invention for manufacturing a field effect transistor can further include the steps of manufacturing a gate insulator, manufacturing source and drain electrodes, and the like. Further, for example, the method of the present invention for producing a solar cell can include a step of producing at least one of an N-type semiconductor and a P-type semiconductor, or an intrinsic semiconductor, a step of forming a current collecting electrode, and the like by the method of the present invention. .

<Example 1>
(Preparation of silicon particle dispersion)
Phosphorus (P) -doped silicon particles were produced by a laser pyrolysis (LP) method using a CO ₂ laser using SiH ₄ gas and PH ₃ gas as raw materials. The obtained phosphorus-doped silicon particles had an average primary particle size of about 15 nm, a particle size distribution of 38 nm ² , and a dopink concentration of 1 × 10 ²¹ atoms / cm ³ . The phosphorus-doped silicon particles were ultrasonically dispersed in isopropyl alcohol (IPA) to obtain a phosphorus-doped silicon particle dispersion having a solid content concentration of 3 wt%.

  The average primary particle size of the silicon particles was observed by TEM observation and image analysis at a magnification of 100,000 times. The average primary particle diameter and dispersion of the silicon particle dispersion were calculated based on a set of 500 or more n.

(Preparation of base material)
Boron (B) -doped silicon substrate (thickness 200 μm, specific resistance 3Ωcm or less) was ultrasonically cleaned in acetone and isopropyl alcohol for 5 minutes each, and the oxide film was removed in 5% hydrogen fluoride aqueous solution for 10 minutes. Then, particles were removed with a cleaning liquid (Frontier Cleaner, manufactured by Kanto Chemical Co., Ltd.) to prepare a cleaned substrate.

(Application)
The silicon particle dispersion was applied to the substrate by dropping several drops of the phosphorus-doped silicon particle dispersion onto the substrate and spin coating at 500 rpm for 5 seconds and 4000 rpm for 10 seconds.

(Dry)
The substrate coated with the phosphorus-doped silicon particle dispersion is dried on a hot plate at 70 ° C. to remove isopropyl alcohol, which is a dispersion medium in the silicon particle dispersion, and thereby unfired containing silicon particles. A sintered silicon particle film (film thickness 300 nm) was formed.

(Light irradiation)
Next, this unsintered silicon particle film was irradiated with a YVO ₄ laser (wavelength 355 nm) in an argon atmosphere using a laser light irradiation device (manufactured by Quantronix, trade name Osprey 355-2-0). The silicon particles in the unsintered silicon particle film were sintered to obtain a first semiconductor silicon film.

Here, the irradiated YVO ₄ laser had a circular section with a diameter of 73 μm, and was scanned on the substrate to sinter the silicon particles. The laser light irradiation conditions were an irradiation energy of 200 mJ / (cm ² · shot), a shot count of 30 times, and an irradiation time of 30 nanoseconds / shot.

(Second application, drying and light irradiation)
With respect to the first semiconductor silicon film obtained as described above, the application and drying of the phosphorus-doped silicon particle dispersion and the light irradiation were repeated as described above to obtain a second semiconductor silicon film.

(Evaluation 1—Surface morphology observation)
The surface morphology of the fabricated second semiconductor silicon film was observed with a field emission scanning electron microscope (FE-SEM) (S5200, manufactured by Hitachi High-Technologies Corporation). The surface morphology observation results are shown in FIG. From FIG. 2, it is observed that this semiconductor silicon film is composed of a plurality of elongated silicon particles adjacent in the minor axis direction.

  Also, from FIG. 2, it can be seen that a substantial part of the elongated silicon particles has a minor axis diameter of 240 nm or more, and a substantial part of the elongated silicon particles has an aspect ratio of more than 1.1. Observed.

(Evaluation 2-Solar cell performance)
An indium-zinc oxide (IZO) thin film (200 nm) as a transparent electrode is formed on both surfaces of the produced substrate having the second semiconductor silicon film by using a sputtering apparatus, and the solar cell shown in FIG. Produced.

  Here, as shown in FIG. 3, in this solar cell (200), a phosphorous (P) doped semiconductor silicon film (220) is laminated on a boron (B) doped silicon substrate (210). The indium-zinc oxide (IZO) thin film (232 and 234) as a transparent electrode is laminated | stacked on the both surfaces.

  The current-voltage (IV) characteristic evaluation of the produced solar cell was performed using a solar simulator (manufactured by Asahi Spectroscope, HAL-320). A variable voltage of −100 to 500 mV was applied between the electrodes, and the change in the current flowing between the electrodes was examined. The results of current-voltage (IV) characteristic evaluation of this solar cell are shown in FIG.

<Reference Example 1>
(Creation of the first semiconductor silicon film)
Only the first semiconductor silicon film was obtained in substantially the same manner as in Example 1 except that silicon particles having a particle size distribution of 52 nm ² were used. That is, here, the application and drying of the silicon particle dispersion and the light irradiation were performed only once.

(Evaluation-Surface morphology observation)
The surface form of the manufactured first semiconductor silicon film was observed in the same manner as in Example 1. The surface morphology observation results are shown in FIG. FIG. 5 confirms that the semiconductor silicon film is composed of a plurality of sintered silicon particles.

<Reference Example 2>
(Creation of the first semiconductor silicon film)
Only the first semiconductor silicon film was obtained in substantially the same manner as in Example 1 except that silicon particles having a particle size distribution of 3 nm ² were used. That is, here, the application and drying of the silicon particle dispersion and the light irradiation were performed only once.

(Evaluation-Surface morphology observation)
The surface form of the manufactured first semiconductor silicon film was observed in the same manner as in Example 1. The surface morphology observation results are shown in FIG. From FIG. 6, it is observed that this semiconductor silicon film has a relatively flat surface.

The particle dispersion of size distribution as in Reference Example 1 using the silicon particles is 52 nm ^2, from the comparison between Reference Example 2 in which the dispersion of the particle size distribution using silicon particles is 3 nm ^2, the dispersion is relatively In Reference Example 1 using large silicon particles, it is observed that the individual sintered silicon particles grow relatively in the vertical direction. Sintered silicon particles grown in such a relatively vertical direction are used as the first semiconductor silicon film in the method of the present invention, and a semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the minor axis direction. It is understood that it is preferable to finally obtain

DESCRIPTION OF SYMBOLS 10 1st silicon particle 12 Sintered silicon particle 15 1st dispersion medium 20 Silicon particle 22 Elongated silicon particle 25 2nd dispersion medium 100 Base material 110 1st silicon particle dispersion film 120 1st unsintered semiconductor Silicon film 130 First semiconductor silicon film 140 Second silicon particle dispersion film 150 Second unsintered semiconductor silicon film 160 Semiconductor silicon film of the present invention 200 Light

Claims (14)

  A semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the minor axis direction, wherein the elongated silicon particles are a sintered body of a plurality of silicon particles.   The semiconductor silicon film according to claim 1, wherein at least a part of the elongated silicon particles has a minor axis diameter of 100 nm or more.   The semiconductor silicon film according to claim 1, wherein at least a part of the elongated silicon particles has an aspect ratio exceeding 1.2.   A semiconductor device comprising the semiconductor silicon film according to claim 1.   The semiconductor device according to claim 4 which is a solar cell. A method for producing a semiconductor silicon film in which a plurality of elongated silicon particles are adjacent in the minor axis direction,
(A) A first silicon particle dispersion containing a first dispersion medium and first silicon particles dispersed in the first dispersion medium is applied onto a substrate to form first silicon Forming a particle dispersion film;
(B) drying the first silicon particle dispersion film to form a first unsintered semiconductor silicon film; and (c) irradiating the first unsintered semiconductor silicon film with light. And sintering the first silicon particles in the first unsintered semiconductor silicon film, thereby forming a first semiconductor silicon film,
(D) applying a second silicon particle dispersion containing a second dispersion medium and second silicon particles dispersed in the second dispersion medium to the first semiconductor silicon film; Forming a second silicon particle dispersion film;
(E) drying the second silicon particle dispersion film to form a second unsintered semiconductor silicon film; and (f) irradiating the second unsintered semiconductor silicon film with light. And sintering the second silicon particles in the second unsintered semiconductor silicon film,
And the dispersion of the first silicon particles is 5 nm ² or more.   The method of Claim 6 that the average primary particle diameter of the said silicon particle is 100 nm or less.   The method according to claim 6 or 7, wherein the silicon particles are silicon particles obtained by a laser pyrolysis method.   The method according to claim 6, wherein the unsintered semiconductor silicon film has a thickness of 50 to 2000 nm.   The method according to any one of claims 6 to 9, wherein the light irradiation is performed using a laser.   The method according to any one of claims 6 to 10, wherein the light irradiation is performed in a non-oxidizing atmosphere.   A semiconductor silicon film obtained by the method according to claim 6.   The manufacturing method of a semiconductor device including making a semiconductor silicon film by the method as described in any one of Claims 6-11.   A semiconductor device obtained by the method of claim 13.